AnatomyAnatomyLecture 4Lecture 4

NeuroanatomyNeuroanatomy

Physician Assistant ProgramPhysician Assistant ProgramMiami Dade CollegeMiami Dade College

““Imagination is everything. Imagination is everything. It is the preview of life’s It is the preview of life’s coming attractions.”coming attractions.”

Albert Einstein Albert Einstein

Division of the BrainDivision of the Brain

Divisions of the BrainDivisions of the Brain

FOREBRAIN (PROSENCEPHALON)TELENCEPHALONDIENCEPHALON

MIDBRAIN (MESENCEPHALON)MESENCEPHALON

HINDBRAIN (RHOMBENCEPHALON))METENCEPHALONMYELENCEPHALON

FOREBRAIN (PROSENCEPHALON) TELENCEPHALON DIENCEPHALON

TELENCEPHALONTELENCEPHALONCerebral HemispheresCerebral Hemispheres

Function: Determines Intelligence

Personality Interpretation of Sensory Impulses

Motor Function Planning and Organization

Touch Sensation Location:

The cerebrum is located in the anterior portion of the forebrain.

It is divided into two hemispheres that are connected by the corpus callosum.

..

DIENCEPHALONDIENCEPHALONFunction: –Chewing –Directs Sense Impulses Throughout the Body –Equilibrium –Eye Movement, Vision –Facial Sensation –Hearing –Phonation –Respiration –Salivation, Swallowing –Smell, Taste

Location: The diencephalon is located between the cerebral

hemispheres and above the midbrainStructures:

Structures of the diencephalon include the thalamus, hypothalamus, the optic tracts, optic chiasma,

infundibulum, 3rd Ventricle, mammillary bodies, posterior pituitary gland and the pineal gland.

DIENCEPHALONDIENCEPHALONThe The thalamusthalamus is a major relay center to is a major relay center to

the cortex for all sensations (sight, etc) the cortex for all sensations (sight, etc) except for smell. except for smell.

The The hypothalamushypothalamus controls many controls many functions including hunger, thirst, pain, functions including hunger, thirst, pain, pleasure and the sex drive. pleasure and the sex drive. – Another key function of the hypothalamus is Another key function of the hypothalamus is

to regulate the pituitary gland, which in turn, to regulate the pituitary gland, which in turn, regulates hormonal levels in the body. regulates hormonal levels in the body.

ThalamusThalamus

MIDBRAIN (MESENCEPHALON) MESENCEPHALON

MESENCEPHALONMESENCEPHALONMidbrainMidbrainFunction:

–Controls Responses to Sight –Eye Movement –Pupil Dilation –Body Movement –Hearing

Location: The mesencephalon is the most rostral portion of the brainstem. It is located between the forebrain

and brainstem.

Structures: The mesencephalon consists of the tectum and

tegmentum.

HINDBRAIN (RHOMBENCEPHALON)) METENCEPHALON

MYELENCEPHALON

METENCEPHALONMETENCEPHALONPonsPons

Function: Arousal

Assists in Controlling Autonomic Functions Relays Sensory Information Between the

Cerebrum and Cerebellum Sleep

Location: The pons is the portion of the brainstem

that is between the midbrain and the medulla oblongata.

PonsPons

METENCEPHALONMETENCEPHALONCerebellumCerebellum

Function: Controls Fine Movement

Coordination Balance and Equilibrium

Muscle Tone Location:

The cerebellum is located just above the brainstem, beneath the occipital lobes at the base of the

skull.

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MYELENCEPHALONMYELENCEPHALONMedulla OblongataMedulla Oblongata

Function: Controls Autonomic Functions

Relays Nerve Signals Between the Brain and Spinal Cord

Location: The medulla oblongata is the lower

portion of the brainstem. It is inferior to the pons and anterior to the

cerebellum.

BrainstemBrainstemFunction:

–Alertness –Arousal –Breathing –Blood Pressure –Contains Most of the Crainal Nerves –Digestion –Heart Rate –Other Autonomic Functions –Relays Information Between the Peripheral Nerves and Spinal Cord to the Upper Parts of the Brain

Location: The brainstem is located at the juncture of the cerebrum

and the spinal column. It consists of the midbrain, the pons and the medulla oblongata.

Headaches and Facial PainHeadaches and Facial Pain

Benign vs. pathologicBenign vs. pathologic

TumorTumor

NeuralgiaNeuralgia

OtalgiaOtalgia

odontalgiaodontalgia

Basal Ganglia and CerebellumBasal Ganglia and Cerebellum The basal ganglia and cerebellum are large collections The basal ganglia and cerebellum are large collections

of nuclei that modify movement on a minute-to-minute of nuclei that modify movement on a minute-to-minute basis. basis.

Motor cortex sends information to both, and both Motor cortex sends information to both, and both structures send information right back to cortex via the structures send information right back to cortex via the thalamus. thalamus. – (Remember, to get to cortex you must go through thalamus.) (Remember, to get to cortex you must go through thalamus.)

The output of the cerebellum is excitatory, while the The output of the cerebellum is excitatory, while the basal ganglia are inhibitory. basal ganglia are inhibitory.

The balance between these two systems allows for The balance between these two systems allows for smooth, coordinated movement, and a disturbance in smooth, coordinated movement, and a disturbance in either system will show up as movement disorders either system will show up as movement disorders

HippocampusHippocampus located inside the temporal lobe (one in located inside the temporal lobe (one in

each side of the brain). each side of the brain). It forms a part of the limbic system and It forms a part of the limbic system and

plays a part in memory and spatial plays a part in memory and spatial navigation. navigation.

Affected in:Affected in:– Alzheimer's diseaseAlzheimer's disease– HypoxiaHypoxia– EncephalitisEncephalitis

Pg 913Pg 913

Pg 909Pg 909

Dura mater (reflections)Dura mater (reflections)1.1. Crista galli Crista galli

2.2. Falx cerebri Falx cerebri

3.3. Sinus sagittalis inferior Sinus sagittalis inferior

4.4. Incisura tentorii - Tentorial incisure Incisura tentorii - Tentorial incisure

5.5. Sinus rectus Sinus rectus

6.6. Confluens sinuum Confluens sinuum

7.7. Tentorium cerebelli Tentorium cerebelli

8.8. Sinus petrosus superior Sinus petrosus superior

9.9. Sinus sphenoparietalis Sinus sphenoparietalis

10.10. Diaphragma sellae Diaphragma sellae

11.11. Arteria carotis interna Arteria carotis interna

12.12. Nervus opticus Nervus opticus

13.13. Foramen magnumForamen magnum

Head InjuryHead Injury

10% of Deaths10% of Deaths

LOCLOC

In 1848, Phineas T. In 1848, Phineas T. Gage,Gage,

during railroad during railroad construction a construction a charge exploded charge exploded and the tamping and the tamping rod when through rod when through his frontal skull, his frontal skull, destroying his destroying his prefrontal cortex. prefrontal cortex. He survived! He survived! Regaining his Regaining his physical health in physical health in a few weeks. a few weeks. However, his However, his personality personality changed changed dramatically." dramatically."

Acute cerebral Acute cerebral contusionscontusions

Two weeks after Two weeks after injuryinjury

Pg 920Pg 920

Epidural hematoma. Usually s/p head trauma.

Brief +LOC, followed by lucid period. Then drowsy/coma/death.

A well-defined biconvex collection of blood (arrows) compresses the left cerebral hemisphere. There is inward displacement of the grey-white junction (arrowheads) and slight rightward displacement of the left lateral ventricle.

Subdural hematomaSubdural hematoma::

a a concaveconcave collection of collection of venous blood between venous blood between the dura and the arachnoidthe dura and the arachnoid – (resulting from tears of the bridging veins that (resulting from tears of the bridging veins that

extend from the subarachnoid space to the dural extend from the subarachnoid space to the dural venous sinuses.)venous sinuses.)

– Patients with cortical atrophy, such as alcoholics and Patients with cortical atrophy, such as alcoholics and the elderly, are more susceptible to subdural the elderly, are more susceptible to subdural hematoma formation when undergoing acceleration-hematoma formation when undergoing acceleration-deceleration forces during deceleration forces during head traumahead trauma. .

– After 2 weeks, patients are defined as having a After 2 weeks, patients are defined as having a chronic subdural hematoma, which appear chronic subdural hematoma, which appear hypodense on a CT scan.hypodense on a CT scan.

Large acute subdural hemorrhage (arrows) revealed by CT scan at the level of the lateral ventricles. The hemorrhage has resulted in midline shift, with marked compression and displacement of the right ventricle (arrowheads). Because of the brain distortion and obstruction of CSF outflow, the left lateral ventricle is dilated (wavy arrows).

Right subdural hemorrhage revealed by MRI. The high intensity (white) hemorrhage has dissected under the temporal lobe, and the midline has been displaced to the left. Note the skull fracture overlying the hematoma.

Chronic bilateral subdural hematoma. This skull X-ray shows areas of calcification adjacent to the inner table of both parietal bones (arrows). The diagnosis was confirmed by CT.

Subarachnoid hemorrhageSubarachnoid hemorrhage:: – results from the disruption of subarachnoid vesselsresults from the disruption of subarachnoid vessels– presents with presents with blood in the cerebrospinal fluidblood in the cerebrospinal fluid. . – Not a space occupying lesion, “pero” can lead to Not a space occupying lesion, “pero” can lead to

increased ICP and acute hydrocephalusincreased ICP and acute hydrocephalus– Patients may complain of Patients may complain of headache, photophobia, headache, photophobia,

and have mild meningeal signsand have mild meningeal signs..– Noncontrast CT is diagnostic in most cases (95%)Noncontrast CT is diagnostic in most cases (95%)– If CT is neg, but clinical suspicion is strong do LPIf CT is neg, but clinical suspicion is strong do LP– ““Worst HA of my life”Worst HA of my life”– ““Thunder-clap HA” Thunder-clap HA” – Sudden OnsetSudden Onset

Subarachnoid Subarachnoid HemorrhageHemorrhage

Diffuse or focally increased ICP:Diffuse or focally increased ICP:– can result in herniation of the brain at several can result in herniation of the brain at several

locations.locations.

Transtentorial (uncal) herniation:Transtentorial (uncal) herniation:– occurs when the uncus of the temporal lobe occurs when the uncus of the temporal lobe

is forced through the tentorial hiatus causing is forced through the tentorial hiatus causing compression of the ipsilateral third cranial compression of the ipsilateral third cranial nerve and the cerebral peduncle.nerve and the cerebral peduncle.

– This leads to a dilated ipsilateral pupil and This leads to a dilated ipsilateral pupil and contra- lateral hemiparesis.contra- lateral hemiparesis.

Post Spinal Tap HeadachePost Spinal Tap Headache

MeningitisMeningitis

Epidural Nerve Block (OB)Epidural Nerve Block (OB)

ReviewReview

A.Subarachnoid ?B.Subdural ? C.Epidural ?

ReviewReview

Subdural

Epidural Subarachnoid

pg1125pg1125

pg1128pg1128

3 3 (SO (SO 44 LR 6) LR 6)

Sympathetic Sympathetic stimulation of stimulation of α1-receptorsα1-receptors

Parasympathetic Parasympathetic axons axons

circular muscle

radial muscle

Five basic tastesFive basic tastes

BitternessBitterness

SaltinessSaltiness

SournessSourness

SweetnessSweetness

UmamiUmami

pg1152pg1152

Horner’s SyndromeHorner’s Syndrome– Lesion of Cervical Sympathetic TrunkLesion of Cervical Sympathetic Trunk– PtosisPtosis– MiosisMiosis– AnhydrosisAnhydrosis

Carotid Sinus MassageCarotid Sinus Massage

StrokeStroke

Ischemic Vs. HemorrhagicIschemic Vs. Hemorrhagic

CVA vs TIACVA vs TIA

AneurysmAneurysm

Berry @ Basilar/Posterior cerebral Berry @ Basilar/Posterior cerebral arteryartery

SAHSAH

'Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence,

but rather we have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an

act but a habit.' AristotleA journey of a thousand miles begins with a single step. A journey of a thousand miles begins with a single step.

   Lao TsuLao Tsu  ““I find that the harder I work, the more luck I seem to I find that the harder I work, the more luck I seem to

have”.have”.   Thomas JeffersonThomas Jefferson

Self conquest is the greatest of victories.Self conquest is the greatest of victories. PlatoPlato

““Imagination is everything. It is the preview of life’s Imagination is everything. It is the preview of life’s coming attractions.”coming attractions.”

Albert EinsteinAlbert Einstein