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Diencephalon
By Rashid Alshahoumi
Outline Overview Development of
Diencephalon Basic Organization Dorsal Thalamus
(Thalamus)
Hypothalamus Ventral Thalamus
( Subthalamus) Epithalamus Vasculature of the
Diencephalon
Diencephalon The diencephalon includes - Dorsal thalamus - Hypothalamus - Ventral thalamus - Epithalamus
Situated between telencephalon amp brainstem
Main processing center for information
Rt amp Lt halves of the diencephaloncontain symmetrically distributed cell groups separated by the space of the 3rd ventricle
Development of the Diencephalon
The cell groups that give rise to the diencephalon form in the caudomedial portion of the prosencephalon bordering on the space that will become the 3rd ventricle
The developing brain at this level consists initially of a roof plate and the two alar plates it lacks a well-defined floor plate and basal plates
The hypothalamic sulcus - A shallow groove appears in the wall of the 3rd ventricle
amp extends rostrally from the developing cerebral aqueduct to the ventral edge of the interventricular foramen
- Divides the alar plate into Superior (dorsal) area future dorsal thalamus Inferior (ventral) portion future hypothalamus
The dorsal thalamus - On each side of the 3rd ventricle increases rapidly in
size amp will partially fuse across the space of the 3rd ventricle to form
- massa intermedia or interthalamic adhesion (present in about 80 of the general population)
The epithalamus - Develops from the caudal portion of the roof plate - By 7th week a small thickening of the roof plate
forms It gradually increases in size amp evaginates to form the epiphysis which develops into the pineal gland of the adult
- The portion of the roof plate immediately rostral to the epiphysis gives rise to the habenula a small thickening in which the habenular nuclei will develop
Just anterior to the habenular region the roof plate epithelium amp adjacent pia mater give rise to the choroid plexus of the third ventricle This choroid plexus is continuous through the interventricular foramina with that of the lateral ventricles
In locations around the perimeter of the 3rd ventricle specialized patches of ependyma lie on the midline amp form unpaired structures called the circumventricular organs
These structures include Subfornical organ Organum vasculosum of the lamina
terminalis Subcommissural organ Pineal gland
The development of the pituitary gland during the 3rd week is linked to that of the diencephalon
A downward extension of the floor of the 3rd ventricle the infundibulum meets the Rathke pouch an upward outpocketing of the stomodeum the primitive oral cavity
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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Outline Overview Development of
Diencephalon Basic Organization Dorsal Thalamus
(Thalamus)
Hypothalamus Ventral Thalamus
( Subthalamus) Epithalamus Vasculature of the
Diencephalon
Diencephalon The diencephalon includes - Dorsal thalamus - Hypothalamus - Ventral thalamus - Epithalamus
Situated between telencephalon amp brainstem
Main processing center for information
Rt amp Lt halves of the diencephaloncontain symmetrically distributed cell groups separated by the space of the 3rd ventricle
Development of the Diencephalon
The cell groups that give rise to the diencephalon form in the caudomedial portion of the prosencephalon bordering on the space that will become the 3rd ventricle
The developing brain at this level consists initially of a roof plate and the two alar plates it lacks a well-defined floor plate and basal plates
The hypothalamic sulcus - A shallow groove appears in the wall of the 3rd ventricle
amp extends rostrally from the developing cerebral aqueduct to the ventral edge of the interventricular foramen
- Divides the alar plate into Superior (dorsal) area future dorsal thalamus Inferior (ventral) portion future hypothalamus
The dorsal thalamus - On each side of the 3rd ventricle increases rapidly in
size amp will partially fuse across the space of the 3rd ventricle to form
- massa intermedia or interthalamic adhesion (present in about 80 of the general population)
The epithalamus - Develops from the caudal portion of the roof plate - By 7th week a small thickening of the roof plate
forms It gradually increases in size amp evaginates to form the epiphysis which develops into the pineal gland of the adult
- The portion of the roof plate immediately rostral to the epiphysis gives rise to the habenula a small thickening in which the habenular nuclei will develop
Just anterior to the habenular region the roof plate epithelium amp adjacent pia mater give rise to the choroid plexus of the third ventricle This choroid plexus is continuous through the interventricular foramina with that of the lateral ventricles
In locations around the perimeter of the 3rd ventricle specialized patches of ependyma lie on the midline amp form unpaired structures called the circumventricular organs
These structures include Subfornical organ Organum vasculosum of the lamina
terminalis Subcommissural organ Pineal gland
The development of the pituitary gland during the 3rd week is linked to that of the diencephalon
A downward extension of the floor of the 3rd ventricle the infundibulum meets the Rathke pouch an upward outpocketing of the stomodeum the primitive oral cavity
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Diencephalon The diencephalon includes - Dorsal thalamus - Hypothalamus - Ventral thalamus - Epithalamus
Situated between telencephalon amp brainstem
Main processing center for information
Rt amp Lt halves of the diencephaloncontain symmetrically distributed cell groups separated by the space of the 3rd ventricle
Development of the Diencephalon
The cell groups that give rise to the diencephalon form in the caudomedial portion of the prosencephalon bordering on the space that will become the 3rd ventricle
The developing brain at this level consists initially of a roof plate and the two alar plates it lacks a well-defined floor plate and basal plates
The hypothalamic sulcus - A shallow groove appears in the wall of the 3rd ventricle
amp extends rostrally from the developing cerebral aqueduct to the ventral edge of the interventricular foramen
- Divides the alar plate into Superior (dorsal) area future dorsal thalamus Inferior (ventral) portion future hypothalamus
The dorsal thalamus - On each side of the 3rd ventricle increases rapidly in
size amp will partially fuse across the space of the 3rd ventricle to form
- massa intermedia or interthalamic adhesion (present in about 80 of the general population)
The epithalamus - Develops from the caudal portion of the roof plate - By 7th week a small thickening of the roof plate
forms It gradually increases in size amp evaginates to form the epiphysis which develops into the pineal gland of the adult
- The portion of the roof plate immediately rostral to the epiphysis gives rise to the habenula a small thickening in which the habenular nuclei will develop
Just anterior to the habenular region the roof plate epithelium amp adjacent pia mater give rise to the choroid plexus of the third ventricle This choroid plexus is continuous through the interventricular foramina with that of the lateral ventricles
In locations around the perimeter of the 3rd ventricle specialized patches of ependyma lie on the midline amp form unpaired structures called the circumventricular organs
These structures include Subfornical organ Organum vasculosum of the lamina
terminalis Subcommissural organ Pineal gland
The development of the pituitary gland during the 3rd week is linked to that of the diencephalon
A downward extension of the floor of the 3rd ventricle the infundibulum meets the Rathke pouch an upward outpocketing of the stomodeum the primitive oral cavity
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Rt amp Lt halves of the diencephaloncontain symmetrically distributed cell groups separated by the space of the 3rd ventricle
Development of the Diencephalon
The cell groups that give rise to the diencephalon form in the caudomedial portion of the prosencephalon bordering on the space that will become the 3rd ventricle
The developing brain at this level consists initially of a roof plate and the two alar plates it lacks a well-defined floor plate and basal plates
The hypothalamic sulcus - A shallow groove appears in the wall of the 3rd ventricle
amp extends rostrally from the developing cerebral aqueduct to the ventral edge of the interventricular foramen
- Divides the alar plate into Superior (dorsal) area future dorsal thalamus Inferior (ventral) portion future hypothalamus
The dorsal thalamus - On each side of the 3rd ventricle increases rapidly in
size amp will partially fuse across the space of the 3rd ventricle to form
- massa intermedia or interthalamic adhesion (present in about 80 of the general population)
The epithalamus - Develops from the caudal portion of the roof plate - By 7th week a small thickening of the roof plate
forms It gradually increases in size amp evaginates to form the epiphysis which develops into the pineal gland of the adult
- The portion of the roof plate immediately rostral to the epiphysis gives rise to the habenula a small thickening in which the habenular nuclei will develop
Just anterior to the habenular region the roof plate epithelium amp adjacent pia mater give rise to the choroid plexus of the third ventricle This choroid plexus is continuous through the interventricular foramina with that of the lateral ventricles
In locations around the perimeter of the 3rd ventricle specialized patches of ependyma lie on the midline amp form unpaired structures called the circumventricular organs
These structures include Subfornical organ Organum vasculosum of the lamina
terminalis Subcommissural organ Pineal gland
The development of the pituitary gland during the 3rd week is linked to that of the diencephalon
A downward extension of the floor of the 3rd ventricle the infundibulum meets the Rathke pouch an upward outpocketing of the stomodeum the primitive oral cavity
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Development of the Diencephalon
The cell groups that give rise to the diencephalon form in the caudomedial portion of the prosencephalon bordering on the space that will become the 3rd ventricle
The developing brain at this level consists initially of a roof plate and the two alar plates it lacks a well-defined floor plate and basal plates
The hypothalamic sulcus - A shallow groove appears in the wall of the 3rd ventricle
amp extends rostrally from the developing cerebral aqueduct to the ventral edge of the interventricular foramen
- Divides the alar plate into Superior (dorsal) area future dorsal thalamus Inferior (ventral) portion future hypothalamus
The dorsal thalamus - On each side of the 3rd ventricle increases rapidly in
size amp will partially fuse across the space of the 3rd ventricle to form
- massa intermedia or interthalamic adhesion (present in about 80 of the general population)
The epithalamus - Develops from the caudal portion of the roof plate - By 7th week a small thickening of the roof plate
forms It gradually increases in size amp evaginates to form the epiphysis which develops into the pineal gland of the adult
- The portion of the roof plate immediately rostral to the epiphysis gives rise to the habenula a small thickening in which the habenular nuclei will develop
Just anterior to the habenular region the roof plate epithelium amp adjacent pia mater give rise to the choroid plexus of the third ventricle This choroid plexus is continuous through the interventricular foramina with that of the lateral ventricles
In locations around the perimeter of the 3rd ventricle specialized patches of ependyma lie on the midline amp form unpaired structures called the circumventricular organs
These structures include Subfornical organ Organum vasculosum of the lamina
terminalis Subcommissural organ Pineal gland
The development of the pituitary gland during the 3rd week is linked to that of the diencephalon
A downward extension of the floor of the 3rd ventricle the infundibulum meets the Rathke pouch an upward outpocketing of the stomodeum the primitive oral cavity
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
The hypothalamic sulcus - A shallow groove appears in the wall of the 3rd ventricle
amp extends rostrally from the developing cerebral aqueduct to the ventral edge of the interventricular foramen
- Divides the alar plate into Superior (dorsal) area future dorsal thalamus Inferior (ventral) portion future hypothalamus
The dorsal thalamus - On each side of the 3rd ventricle increases rapidly in
size amp will partially fuse across the space of the 3rd ventricle to form
- massa intermedia or interthalamic adhesion (present in about 80 of the general population)
The epithalamus - Develops from the caudal portion of the roof plate - By 7th week a small thickening of the roof plate
forms It gradually increases in size amp evaginates to form the epiphysis which develops into the pineal gland of the adult
- The portion of the roof plate immediately rostral to the epiphysis gives rise to the habenula a small thickening in which the habenular nuclei will develop
Just anterior to the habenular region the roof plate epithelium amp adjacent pia mater give rise to the choroid plexus of the third ventricle This choroid plexus is continuous through the interventricular foramina with that of the lateral ventricles
In locations around the perimeter of the 3rd ventricle specialized patches of ependyma lie on the midline amp form unpaired structures called the circumventricular organs
These structures include Subfornical organ Organum vasculosum of the lamina
terminalis Subcommissural organ Pineal gland
The development of the pituitary gland during the 3rd week is linked to that of the diencephalon
A downward extension of the floor of the 3rd ventricle the infundibulum meets the Rathke pouch an upward outpocketing of the stomodeum the primitive oral cavity
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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The epithalamus - Develops from the caudal portion of the roof plate - By 7th week a small thickening of the roof plate
forms It gradually increases in size amp evaginates to form the epiphysis which develops into the pineal gland of the adult
- The portion of the roof plate immediately rostral to the epiphysis gives rise to the habenula a small thickening in which the habenular nuclei will develop
Just anterior to the habenular region the roof plate epithelium amp adjacent pia mater give rise to the choroid plexus of the third ventricle This choroid plexus is continuous through the interventricular foramina with that of the lateral ventricles
In locations around the perimeter of the 3rd ventricle specialized patches of ependyma lie on the midline amp form unpaired structures called the circumventricular organs
These structures include Subfornical organ Organum vasculosum of the lamina
terminalis Subcommissural organ Pineal gland
The development of the pituitary gland during the 3rd week is linked to that of the diencephalon
A downward extension of the floor of the 3rd ventricle the infundibulum meets the Rathke pouch an upward outpocketing of the stomodeum the primitive oral cavity
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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In locations around the perimeter of the 3rd ventricle specialized patches of ependyma lie on the midline amp form unpaired structures called the circumventricular organs
These structures include Subfornical organ Organum vasculosum of the lamina
terminalis Subcommissural organ Pineal gland
The development of the pituitary gland during the 3rd week is linked to that of the diencephalon
A downward extension of the floor of the 3rd ventricle the infundibulum meets the Rathke pouch an upward outpocketing of the stomodeum the primitive oral cavity
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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The development of the pituitary gland during the 3rd week is linked to that of the diencephalon
A downward extension of the floor of the 3rd ventricle the infundibulum meets the Rathke pouch an upward outpocketing of the stomodeum the primitive oral cavity
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
By the end of the 2nd month the Rathke pouch loses its connection with the developing oral cavity but maintains its attachment to the infundibulum
As development continues the Rathke pouch gives rise to the anterior lobe (adenohypophysis) and pars intermedia of the pituitary gland
Infundibulum differentiates into the posterior lobe of the pituitary gland or neurohypophysis
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
A craniopharyngioma (Rathke pouch tumor) can arise from a portion of the Rathke pouch that fails to undergo proper migration amp apposition to the infundibulum
These tumors mimic lesions of the pituitary amp may cause visual problems diabetes insipidus amp uarr ICP
Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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Basic Organization The junction between the diencephalon amp midbrain lies along a line
extending from the posterior commissure to the caudal edge of the mammillary body on the medial aspect of the hemisphere
On the surface of the hemisphere this interface is represented by a line starting at the caudal aspect of the mammillary body extending anterolaterally over the edge of the crus cerebri amp following the caudal edge of the optic tract
The boundary between the diencephalon amp surrounding telencephalon is less distinct amp represented
- laterally by the internal capsule - rostrally by the interventricular foramen lamina terminalis amp optic
chiasm
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
The 3rd third ventricle has small evaginations or recesses associated with
- Optic chiasm (supraoptic recess)
- Infundibulum (infundibular recess)
- Pineal gland (pinealamp suprapineal recesses)
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
The dorsal thalamus Located superior to the hypothalamic sulcus Extends from the interventricular foramen
caudally to the level of the splenium of the corpus callosum
The hypothalamus Located inferior to the hypothalamic sulcus Bordered - Rostrally by the lamina terminalis - Caudally by a line that extends from the
posterior aspect of the mammillary body - Superiorly to intersect with the hypothalamic
sulcus
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
The ventral thalamus (subthalamus) Located - Caudal to the hypothalamus- Rostral to the diencephalon-midbrain junction- Lateral to the midline
Epithalamic structures Located posteriorly amp caudally in close apposition to the
posterior commissure Include - pineal gland - habenular nuclei - main afferent bundle of these nuclei - stria medullaris thalami
Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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Dorsal Thalamus (Thalamus) The dorsal thalamus (or thalamus) is a
massive collection of neuronal cell groups that participate in a widely diverse array of functions involving motor sensory amp limbic systems
Typically thalamic output neurons project to the cerebral cortex rarr very little information reaches the cerebral cortex without first being processed by thalamic neuronsrarr the thalamus is functional gateway to the cerebral cortex
In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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In turn nearly all regions of the cerebral cortex give rise to reciprocal projections that return to the thalamic region from which they originally received input
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
The thalamus is covered on its lateral aspect by a layer of myelinated axons the external medullary lamina ( includes fibers that enter or leave the subcortical white matter)
Within the external medullary lamina are clusters of neurons that form the thalamic reticular nucleus
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
An internal medullary lamina
- Consisting of myelinated fibers
- Extends into the substance of the thalamus where it forms partitions or boundaries that divide the thalamus into its principal cell groups
- anterior medial lateral amp intraluminar nuclear groups
There are midline thalamic nuclei located just superior to the hypothalamic sulcus
Finally attached to the caudolateral portion of the thalamus are the medial and lateral geniculate bodies (and their nuclei)
Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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Anterior Thalamic Nuclei This group of cells consists of a large
principal nucleus amp two smaller nuclei rarr form the anterior nucleus of the thalamus
The anterior nucleus forms a prominent wedge on the rostral aspect of the dorsal thalamus just caudolateral to the interventricular foramen rarr this wedge is the anterior thalamic tubercle
Rostrally the internal medullary lamina divides to partially encapsulate the anterior nucleus
Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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Anterior Thalamic Nuclei The cells of this nucleus receive dense
limbic-related projections from (1) the mammillary nuclei via the mammillothalamic tract and (2) the medial temporal lobe (hippocampus) via the fornix
The output of this nucleus is primarily directed to the cingulate gyrus through the anterior limb of the internal capsule
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Medial Thalamic Nuclei Comprises the dorsomedial nucleus Composed of -Large parvicellular (located caudally) -Magnocellular (located rostrally) -Small paralaminar adjacent to the internal
medullary lamina 2 larger portions are linked to parts of the
frontal amp temporal lobes amp to the amygdaloid complex
Cells of the paralaminar subdivision receive input from the frontal lobe amp substantia nigra
(may play a role in the control of eye movement)
Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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Lateral Thalamic Nuclei 2 subdivisions2 subdivisions Dorsal subdivision
Lateral dorsal
- Functionally part of anterior group (limbic system)
Lateral posterior
Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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Inputs1048708 Pretectal area1048708 Superior colliculus
Roles1048708 Visual relay center1048708 Selective attention1048708 Speech
Pulvinar Border with lateral posterior is vague
Reciprocal
connections
1048708 Lateral geniculate nucleus
1048708 Parietal lobe1048708 Temporal lobe1048708 Occipital lobe
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Ventral subdivision- Ventral anterior
- Ventral lateral
- Ventral posterior Receive direct input from long
ascending tracts Reprocal connections with cortex Retrograde degeneration on cortical
lesions
Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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Ventral Anterior Input
1048708 Globus pallidus
1048708 Substantia nigra
1048708 Intralaminar nucleus (thalamus)
1048708 Premotorprefrontal cortex
Output (reciprocal connections)
1048708 Premotor cortex
1048708 Prefrontal cortex
1048708 Intralaminar nucleus
Roles
1048708 Motor relay station
- Regulate movement
(Control of voluntary movement)
1048708 Medial part
- Eye head neck
1048708 Lateral part
- Body limb
Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
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Ventral Lateral Nucleus Input 1048708Deep cerebellar nuclei 1048708Globus pallidus 1048708Primary motor cortex
Output 1048708Primary motor cortex(reciprocal) 1048708Parietal lobe -Somatosensory areas 1048708PremotorSupplementarymotor areas
Role1048708 Motor relay station - Cerebellumbasal
gangliacortex
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Ventral Posterior Nucleus 2 Divisions Ventral posterior medial
(VPM) Ventral posterior lateral
(VPL)
Inputs1048708 Medial lemniscus - VPL1048708 Spinothalamic -VPL1048708 Trigeminal lemniscus (taste) - VPM1048708 Primary somatosensory
cortex - VPM amp VPL
Output1048708 Primary somatosensory
cortex (reciprocal)1048708 Parietal operculum (taste)
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
The lateral (The lateral (LGBLGB) and medial ) and medial (MGB(MGB) geniculate ) geniculate nuclei are considered parts of the lateral nuclei are considered parts of the lateral thalamic nuclear group thalamic nuclear group
MGBMGB receives ascending receives ascending auditoryauditory input via the input via the brachium of the inferior colliculus brachium of the inferior colliculus rarrrarr projects to projects to the primary auditory cortex in the temporal the primary auditory cortex in the temporal lobe lobe
LGBLGB receives receives visualvisual input from the retina via input from the retina via the optic tract the optic tract rarr rarr projects to the primary visual projects to the primary visual cortex on the medial surface of the occipital cortex on the medial surface of the occipital lobe lobe
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Located in the posterior thalamus at about the Located in the posterior thalamus at about the level of the pulvinar and geniculate nuclei is a level of the pulvinar and geniculate nuclei is a cluster of cell groups collectively called the cluster of cell groups collectively called the posterior nuclear complexposterior nuclear complex
This complex consists of This complex consists of - - Suprageniculate nucleusSuprageniculate nucleus- Nucleus limitansNucleus limitans- Posterior nucleus Posterior nucleus These nuclei are positioned superior to the These nuclei are positioned superior to the
medial geniculate and medial to the rostral medial geniculate and medial to the rostral pulvinarpulvinar
The posterior nuclear complex receivesamp sends The posterior nuclear complex receivesamp sends
to the cortex nociceptive cutaneous input that to the cortex nociceptive cutaneous input that is transmitted over somatosensory pathwaysis transmitted over somatosensory pathways
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Intralaminar NucleiIntralaminar Nuclei Embedded within the internal medullary lamina are the Embedded within the internal medullary lamina are the
discontinuous groups of neurons that form the discontinuous groups of neurons that form the intralaminar nucleiintralaminar nuclei
Projections to the neostriatum amp to other thalamic nuclei Projections to the neostriatum amp to other thalamic nuclei along with diffuse projections to the cerebral cortex along with diffuse projections to the cerebral cortex
2 of the most prominent cell groups are 2 of the most prominent cell groups are - CentromedianCentromedian projects to the neostriatum amp to motor projects to the neostriatum amp to motor
areas of the cerebral cortex areas of the cerebral cortex - Parafascicular nucleiParafascicular nuclei projects to rostral amp lateral areas of projects to rostral amp lateral areas of
the frontal lobethe frontal lobe
Other intralaminar nuclei receive input from ascending Other intralaminar nuclei receive input from ascending pain pathways and project to somatosensory and parietal pain pathways and project to somatosensory and parietal cortexcortex
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Midline NucleiMidline Nuclei The midline nuclei are the least understood components The midline nuclei are the least understood components
of the thalamusof the thalamus
The largest is the The largest is the paratenial nucleusparatenial nucleus which is located which is located just ventral to the rostral portion of the stria medullaris just ventral to the rostral portion of the stria medullaris thalami other cells are associated with the interthalamic thalami other cells are associated with the interthalamic adhesion (massa intermedia) adhesion (massa intermedia)
Inputs are poorly definedInputs are poorly defined
Efferent fibers reach the amygdaloid complex ampthe Efferent fibers reach the amygdaloid complex ampthe anterior cingulate cortex suggesting a role in the limbic anterior cingulate cortex suggesting a role in the limbic system system
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Thalamic Reticular NucleusThalamic Reticular Nucleus The cells are situated within the external medullary The cells are situated within the external medullary
lamina amp between this lamina and the internal capsule lamina amp between this lamina and the internal capsule
Axons of these cells project medially into the nuclei of Axons of these cells project medially into the nuclei of the dorsal thalamus or to other parts of the reticular the dorsal thalamus or to other parts of the reticular nucleus but not into the cerebral cortexnucleus but not into the cerebral cortex
Afferents are received from the cortex and from nuclei of Afferents are received from the cortex and from nuclei of the dorsal thalamus via collaterals of thalamocortical amp the dorsal thalamus via collaterals of thalamocortical amp corticothalamic axonscorticothalamic axons
Thalamic reticular neurons modulate or gate the Thalamic reticular neurons modulate or gate the responses of thalamic neurons to incoming cerebral responses of thalamic neurons to incoming cerebral cortical input cortical input
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Thalamic nucleus efferent projections Thalamic nucleus efferent projections (thalamocortical axons) rarr corterx(thalamocortical axons) rarr corterx
Cortex rarr reciprocal projection (corticothalamic Cortex rarr reciprocal projection (corticothalamic axons) rarr thalamic nucleusaxons) rarr thalamic nucleus
VLmotorprecentral gyrus and anterior paracentral VLmotorprecentral gyrus and anterior paracentral gyrusgyrus
VPLsensory for the bodypostcentral gyrus and VPLsensory for the bodypostcentral gyrus and posterior paracentral gyrusposterior paracentral gyrus
VPMsensory for the facepostcentral gyrusVPMsensory for the facepostcentral gyrus MGBauditorytransverse temporal gyrusMGBauditorytransverse temporal gyrus LGBvisioncortex on the calcarine sulcusLGBvisioncortex on the calcarine sulcus The anterior nucleus projects primarily to the The anterior nucleus projects primarily to the
cingulate gyrus and functions in the broad area of cingulate gyrus and functions in the broad area of behaviorbehavior
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Thalamic nuclei Thalamic nuclei relay nuclei relay nuclei or or association nucleiassociation nuclei
Thalamic nuclei Thalamic nuclei specificspecific or or nonspecificnonspecific
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
HypothalamusHypothalamus
The hypothalamus is mainly involved in The hypothalamus is mainly involved in visceromotor viscerosensory ampvisceromotor viscerosensory amp endocrineendocrine activities activities
The hypothalamus amp related limbic structures The hypothalamus amp related limbic structures receive sensory input regarding the internal receive sensory input regarding the internal environment amp in turn regulate through four environment amp in turn regulate through four mechanisms the motor systems that modify mechanisms the motor systems that modify the internal environmentthe internal environment
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
HypothalamusHypothalamus
Is a principal modulator of Is a principal modulator of autonomic nervous autonomic nervous system functionsystem function
Is a viscerosensory Is a viscerosensory transducer containing transducer containing neurons with specialized neurons with specialized receptors capable of receptors capable of responding to changes in responding to changes in the temperature or the temperature or osmolality of blood as osmolality of blood as well as to specific well as to specific hormonal levels in the hormonal levels in the general circulation general circulation
It regulates the activity of It regulates the activity of the anterior pituitary the anterior pituitary through the production of through the production of releasing factors releasing factors (hormone-releasing (hormone-releasing hormones) hormones)
It performs an endocrine It performs an endocrine function by producing amp function by producing amp releasing oxytocin releasing oxytocin ampvasopressin into the ampvasopressin into the general circulation within general circulation within the posterior pituitarythe posterior pituitary
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
bull The hypothalamus can be divided into lateral medial amp periventricular zones
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Lateral Hypothalamic ZoneLateral Hypothalamic Zone
Composed of diffuse clusters of neurons Composed of diffuse clusters of neurons intermingled with longitudinally oriented intermingled with longitudinally oriented axon bundlesaxon bundles
Cells are involved in cardiovascular Cells are involved in cardiovascular function amp in the regulation of food amp water function amp in the regulation of food amp water intakeintake
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Medial Hypothalamic ZoneMedial Hypothalamic Zone In contrast to the lateral zone it contains In contrast to the lateral zone it contains discrete groups of neurons whose function amp discrete groups of neurons whose function amp connections are establishedconnections are established Within the Within the chiasmaticchiasmatic (anterior) (anterior) regionregion are 5 are 5 nuclei nuclei
- Preoptic Preoptic - supraopticsupraoptic- paraventricularparaventricular- Anterior Anterior - SuprachiasmaticSuprachiasmatic
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
(Preoptic supraoptic periventricular) rarr (Preoptic supraoptic periventricular) rarr are generally involved in regulating are generally involved in regulating hormone release hormone release
Anterior rarr cardiovascular functionAnterior rarr cardiovascular function
Suprachiasmatic rarr circadian rhythms Suprachiasmatic rarr circadian rhythms
Preoptic rarr body temperature amp heat loss Preoptic rarr body temperature amp heat loss mechanismsmechanisms
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
In the In the tuberal regiontuberal region - Dorsomedial Dorsomedial - VentromedialVentromedial- Arcuate nucleiArcuate nuclei
The The ventromedial nucleusventromedial nucleus - Food intake (satiety) center Food intake (satiety) center - Bilateral lesions produce Bilateral lesions produce hyperphagiahyperphagia a greatly a greatly
increased food intake with resultant obesityincreased food intake with resultant obesity
Cells of the Cells of the arcuate nucleusarcuate nucleus deliver deliver peptidespeptides to to the portal vessels amp through these channels to the portal vessels amp through these channels to the anterior pituitary the anterior pituitary
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Peptides
Releasing factors thatReleasing factors that
uarr uarr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitaryby the anterior pituitary
Inhibiting factors that Inhibiting factors that
darr darr secretion of secretion of
specific hormonesspecific hormones
by the anterior pituitary by the anterior pituitary
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
At caudal levels the At caudal levels the mammillary regionmammillary region - Posterior nucleus- Posterior nucleus - M- Mammillary nucleiammillary nuclei
The mammillary nuclei consist of a large The mammillary nuclei consist of a large medial amp a small lateral nucleusmedial amp a small lateral nucleus Although both of these nuclei receive Although both of these nuclei receive input via the fornix only the medial input via the fornix only the medial nucleus projects to the anterior thalamic nucleus projects to the anterior thalamic nucleus through the mammillothalamic nucleus through the mammillothalamic tracttract
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
The neurons of the posterior nucleus are The neurons of the posterior nucleus are involved in involved in
- uarr uarr BP BP - Pupillary dilationPupillary dilation- Shivering or body heat conservation Shivering or body heat conservation
The mammillary nuclei are involved inThe mammillary nuclei are involved in- Control of various reflexes associated with Control of various reflexes associated with
feedingfeeding- Mechanisms relating to memory formation Mechanisms relating to memory formation
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Afferent Fiber SystemsAfferent Fiber Systems The fornix amp stria terminalis are 2 major afferent fiber are 2 major afferent fiber
bundles that reach the hypothalamus bundles that reach the hypothalamus
The The fornixfornix consists of axons that largely originate in the consists of axons that largely originate in the hippocampus and the hippocampus and the stria terminalisstria terminalis arises from arises from neurons in the amygdaloid complex neurons in the amygdaloid complex
Fibers composing the Fibers composing the ventral amygdalofugal bundleventral amygdalofugal bundle exit exit the amygdala and course through the substantia the amygdala and course through the substantia innominata to enter the hypothalamus and thalamus innominata to enter the hypothalamus and thalamus
The The medial forebrain bundlemedial forebrain bundle passes bidirectionally passes bidirectionally through the lateral hypothalamic region through the lateral hypothalamic region
Ascending axons rarr forebrain amp brainstemAscending axons rarr forebrain amp brainstem
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Efferent FibersEfferent Fibers Several nuclei give rise to descending fibers that Several nuclei give rise to descending fibers that
contribute to the dorsal longitudinal fasciculus and the contribute to the dorsal longitudinal fasciculus and the medial forebrain bundle and to diffuse projections that medial forebrain bundle and to diffuse projections that pass into the tegmentum pass into the tegmentum
These fiber systems project directly to numerous These fiber systems project directly to numerous brainstem nuclei as well as to preganglionic sympathetic brainstem nuclei as well as to preganglionic sympathetic and parasympathetic neurons in the spinal cordand parasympathetic neurons in the spinal cord
Other projections reach the thalamus and frontal cortex Other projections reach the thalamus and frontal cortex and still others extend to the posterior pituitary or to the and still others extend to the posterior pituitary or to the tuberohypophysial portal system for delivery of tuberohypophysial portal system for delivery of substances to the anterior pituitarysubstances to the anterior pituitary
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus) 3 main structures3 main structures 1048708 1048708 Subthalamic Subthalamic
nucleinuclei InputsInputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Cerebral cortexCerebral cortex 1048708 1048708 ThalamusThalamus 1048708 1048708 Reticular formationReticular formation 1048708 1048708 ContralateralContralateral subthalamic nucleussubthalamic nucleus 1048708 1048708 supramamillarysupramamillary commisurecommisure
OutputsOutputs 1048708 1048708 Globus pallidusGlobus pallidus 1048708 1048708 Substantia nigraSubstantia nigra HemiballismusHemiballismus 1048708 1048708 DamageDamage 1048708 1048708 Involuntary violentInvoluntary violent hyperkinesia ofhyperkinesia of contralateral upper ampcontralateral upper amp lower extremitieslower extremities
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Fields of ForelFields of Forel
H field of ForelH field of Forel
1048708 1048708 PrerubralPrerubral H1 field of ForelH1 field of Forel
1048708 1048708 Thalamic fasciculusThalamic fasciculus H2 field of ForelH2 field of Forel
1048708 1048708 Lenticular fasciculusLenticular fasciculus
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Ventral Thalamus (Subthalamus)Ventral Thalamus (Subthalamus)
3 main structures3 main structures
1048708 1048708 Zona incertaZona incerta
1048708 1048708 Implicated in many functions Implicated in many functions LocomotionLocomotion Oculomotor arousalOculomotor arousal Attention feedingAttention feeding SociosexualSociosexual SomatosensorySomatosensory
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
EpithalamusEpithalamus Principal components Principal components - Pineal glandPineal gland- Habenular nucleiHabenular nuclei- Stria medullaris thalamiStria medullaris thalami
The pineal gland consists of richly vascularized The pineal gland consists of richly vascularized connective tissue containing glial cells amp connective tissue containing glial cells amp pinealocytes pinealocytes but no true neurons but no true neurons
PinealocytesPinealocytes are cells that synthesize melatonin are cells that synthesize melatonin from serotonin via enzymes that are sensitive to from serotonin via enzymes that are sensitive to diurnal fluctuations in light diurnal fluctuations in light
Production of melatonin by pinealocytes is Production of melatonin by pinealocytes is rhythmic amp calibrated to the 24-hour cycle of rhythmic amp calibrated to the 24-hour cycle of photic input to the retina = photic input to the retina = circadian rhythmcircadian rhythm
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
EpithalamusEpithalamus The habenular nuclei consist of a large lateral The habenular nuclei consist of a large lateral
nucleus and a small medial nucleus nucleus and a small medial nucleus Both nuclei contribute axons to the Both nuclei contribute axons to the
habenulointerpeduncular tracthabenulointerpeduncular tract (fasciculus (fasciculus retroflexus) which terminates in the midbrain retroflexus) which terminates in the midbrain interpeduncular nucleus interpeduncular nucleus
The The stria medullaris thalamistria medullaris thalami conveys input to conveys input to both habenular nuclei both habenular nuclei
The The habenular commissurehabenular commissure a small bundle of a small bundle of fibers riding on the upper edge of the posterior fibers riding on the upper edge of the posterior commissure connects the habenular regions of commissure connects the habenular regions of the two sidesthe two sides
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Vasculature of the Vasculature of the DiencephalonDiencephalon
The diencephalon is supplied by The diencephalon is supplied by
- Smaller vessels that branch from the Smaller vessels that branch from the various arteries making up the cerebral various arteries making up the cerebral arterial circlearterial circle (circle of Willis) (circle of Willis)
- Larger arteries that originate from the Larger arteries that originate from the proximal parts of the posterior cerebral proximal parts of the posterior cerebral arteryartery
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
The hypothalamus amp subthalamus The hypothalamus amp subthalamus are supplied by are supplied by central branchescentral branches of of the circle the circle (perforating or ganglionic)(perforating or ganglionic)
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Caudal hypothalamic Caudal hypothalamic regions and the regions and the ventral thalamus are ventral thalamus are supplied by branches supplied by branches of the (of the (posteromedial posteromedial group)group)
arising from the arising from the posterior posterior communicating artery communicating artery and the P1 segment of and the P1 segment of the posterior cerebral the posterior cerebral arteryartery
Anterior parts of the Anterior parts of the hypothalamus are hypothalamus are served by central served by central branches branches (anteromedial (anteromedial group)group)
arising from the arising from the anterior communicating anterior communicating artery and the A1 artery and the A1 segment of the anterior segment of the anterior cerebral artery and cerebral artery and from branches of the from branches of the proximal part of the proximal part of the posterior posterior communicating arterycommunicating artery
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Some of the branches of the Some of the branches of the posteromedial groupposteromedial group that arise from that arise from the P1 segment near the basilar the P1 segment near the basilar bifurcation are called the bifurcation are called the thalamoperforating arteriesthalamoperforating arteries
Supply Supply rarr rarr rostral areas of the rostral areas of the thalamus thalamus
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Slightly more distal branches which Slightly more distal branches which usually arise from the P2 segment are the usually arise from the P2 segment are the posterior choroidalposterior choroidal and and thalamogeniculatethalamogeniculate arteriesarteries
Supply Supply rarr rarr portions of the diencephalon portions of the diencephalon A narrow portion of the caudal and medial A narrow portion of the caudal and medial
thalamus bordering on the 3thalamus bordering on the 3rdrd ventricle is ventricle is supplied by the supplied by the medial posterior choroidal medial posterior choroidal arteryartery whereas the thalamogeniculate whereas the thalamogeniculate branches irrigate the caudal thalamus branches irrigate the caudal thalamus including the pulvinar amp geniculate nucleiincluding the pulvinar amp geniculate nuclei
Branches of the medial posterior choroidal Branches of the medial posterior choroidal artery also serve the choroid plexus of the artery also serve the choroid plexus of the 33rdrd ventricle ventricle
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
The The anterior choroidal arteryanterior choroidal artery originates fromoriginates from
Cerebral portion of the internal Cerebral portion of the internal carotid arterycarotid artery
Sends penetrating branches into the Sends penetrating branches into the genugenu amp amp posterior limbposterior limb of the internal of the internal capsule capsule
Serves the optic tract inferior Serves the optic tract inferior portions of the lenticular nucleus the portions of the lenticular nucleus the choroid plexus of the inferior horn of choroid plexus of the inferior horn of the lateral ventricle and large parts of the lateral ventricle and large parts of the hippocampal formationthe hippocampal formation
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Although the thalamus receives a Although the thalamus receives a blood supply largely separate from blood supply largely separate from that of the internal capsule vascular that of the internal capsule vascular lesions in the thalamus may extend lesions in the thalamus may extend into the internal capsule or vice into the internal capsule or vice versa versa
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Ischemic or hemorrhagic strokes in Ischemic or hemorrhagic strokes in the hemisphere may result in the hemisphere may result in contralateral hemiparesiscontralateral hemiparesis in in combination with combination with hemianesthesiahemianesthesia
These losses correlate with damage These losses correlate with damage to corticospinal and thalamocortical to corticospinal and thalamocortical fibers in the internal capsule fibers in the internal capsule
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Strokes involving the larger thalamic Strokes involving the larger thalamic arteries such as the arteries such as the thalamogeniculate artery may result thalamogeniculate artery may result in total or dissociated sensory losses in total or dissociated sensory losses
These patients may subsequently These patients may subsequently experience persistent intense pain experience persistent intense pain (thalamic pain Dejerine-Roussy (thalamic pain Dejerine-Roussy syndrome)syndrome)
Thank YouThank You
Thank YouThank You
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