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© 2012 Pearson Education, Inc.

16The Nervous System: The Brain and Cranial Nerves

PowerPoint® Lecture Presentations prepared bySteven BassettSoutheast Community College Lincoln, Nebraska


Introduction

• The brain is a complex three-dimensionalstructure that performs a bewildering array of functions

• The brain consists of roughly 20 billion neurons


Table 16.1 Development of the Human Brain


Figure 16.1 Major Divisions of the Brain

CEREBRUM

DIENCEPHALON

MESENCEPHALON

PONS

MEDULLA OBLONGATA

CEREBELLUM

• Coordinates complex somatic motor patterns• Adjusts output of other somatic motor centers in brain and spinal cord

Spinalcord

Brainstem

• Relays sensory information to thalamus and to other portions of the brain stem• Autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities)

• Relays sensory information to cerebellum and thalamus• Subconscious somatic and visceral motor centers

• Processing of visual and auditory data• Generation of reflexive somatic motor responses• Maintenance of consciousness

• Centers controlling emotions, autonomic functions, and hormone production

• Relay and processing centers for sensory information

THALAMUS

HYPOTHALAMUS

• Conscious thought processes, intellectual functions• Memory storage and processing• Conscious and subconscious regulation of skeletal muscle contractions

Left cerebralhemisphere

Gyri

Sulci

Fissures


An Introduction to the Organization of the Brain

• Major Regions and Landmarks of the Brain• Medulla oblongata• Pons• Cerebellum• Mesencephalon (midbrain)• Diencephalon • Cerebrum (telencephalon)


Figure 16.13a Sectional Views of the Brain

MesencephalonPons

Temporal lobe

Mamillary body

Optic chiasm

Anteriorcommissure

Frontal lobe

Interventricularforamen

Septumpellucidum

Corpus callosum

Precentral gyrus Central sulcus Postcentral gyrusCingulate gyrus

FornixThalamus

Membranous portionof epithalamusHypothalamus

Pineal gland

Parieto-occipitalsulcus

Superiorcolliculus

CorporaquadrigeminaInferior

colliculus

Aqueductof midbrain

Fourth ventricle

Cerebellum

Medullaoblongata

A sagittal section through the brain



• Medulla oblongata• Relays information to the thalamus and brain

stem• Regulates visceral function

• Pons• Relays information to the thalamus and

cerebellum• Regulates subconscious somatic and visceral

motor centers



• Cerebellum• Coordinates somatic motor function• Adjusts output of somatic motor centers

resulting in smooth operation

• Mesencephalon (midbrain)• Processes visual and auditory data• Maintains consciousness and alertness



• Diencephalon• Epithalamus

• Contains the pineal gland

• Thalamus• Relays information to the cerebrum• Processes sensory information

• Hypothalamus• Involved in emotions, thirst, some habitual activity



• Telencephalon (cerebrum)• Conscious thought processes• Memory storage• Conscious regulation of skeletal muscle

contractions


Figure 16.1 Major Divisions of the Brain

CEREBRUM

DIENCEPHALON

MESENCEPHALON

PONS

MEDULLA OBLONGATA

CEREBELLUM

• Coordinates complex somatic motor patterns• Adjusts output of other somatic motor centers in brain and spinal cord

Spinalcord

Brainstem

• Relays sensory information to thalamus and to other portions of the brain stem• Autonomic centers for regulation of visceral function (cardiovascular, respiratory, and digestive system activities)

• Relays sensory information to cerebellum and thalamus• Subconscious somatic and visceral motor centers

• Processing of visual and auditory data• Generation of reflexive somatic motor responses• Maintenance of consciousness

• Centers controlling emotions, autonomic functions, and hormone production

• Relay and processing centers for sensory information

THALAMUS

HYPOTHALAMUS

• Conscious thought processes, intellectual functions• Memory storage and processing• Conscious and subconscious regulation of skeletal muscle contractions


Gyri

Sulci

Fissures



• The Ventricles of the Brain• Ventricles are fluid-filled cavities

• Filled with cerebrospinal fluid (CSF)

• Fluid transports nutrients to the CNS and transports waste away from the CNS

• CSF also provides protection

• There are four ventricles• Ventricles 1 and 2 (called lateral ventricles) are in the

cerebral hemispheres (separated by a partition called the septum pellucidum)

• Ventricle 3 is in the diencephalon

• Ventricle 4 lies between the pons and the cerebellum


Figure 16.2a Ventricles of the Brain

Orientation and extent of the ventricles asseen in a lateral view of a transparent brain

Anteriorhornsof lateralventricles

Cerebralhemispheres

Pons

Medulla oblongata

Central canalSpinal cord

Lateral ventricles


Third ventricle

Posterior horns oflateral ventricles

Inferior horns oflateral ventricles

Aqueduct ofmidbrain

Fourthventricle

Cerebellum


Figure 16.2c Ventricles of the Brain

Anterior view of the ventricles as ifseen through a transparent brain

Thirdventricle

Aqueduct ofmidbrain

Fourthventricle

Cerebellum

Central canal

Medulla oblongata

Pons


Longitudinalfissure

Lateral ventricles incerebral hemispheres

Inferior horns oflateral ventricles


Figure 16.2d Ventricles of the Brain

Diagrammatic coronal section showing theinterconnections between the ventricles

Lateral ventricles


Thirdventricle

Inferior horn oflateral ventricle

Aqueduct ofmidbrain

Fourthventricle

Septumpellucidum

Central canal


Protection and Support of the Brain

• Protection involves:• Bones of the skull

• Parietal, frontal, occipital, and temporal bones

• Cranial meninges• Dura mater, arachnoid mater, and pia mater

• Cerebrospinal fluid• CSF is produced by choroid plexus in the brain

ventricles.• CSF is drained at arachnoid granulation into the

dural sinuses.

• Blood–brain barrier


Figure 16.3a Relationships among the Brain, Cranium, and Meninges

Lateral view of the brainshowing its position in thecranium and the organizationof the meningeal coverings

Spinal cord

Medulla oblongata

Cerebellum

Cerebralcortex

Cerebralcortex

Piamater

Subarachnoidspace

Cranium Dura mater(endosteal layer)

Dural sinus

Dura mater(meningeal layer)

Subdural space

Arachnoidmater


Figure 16.3b Relationships among the Brain, Cranium, and Meninges

A corresponding view of the cranial cavity with thebrain removed showing the orientation and extentof the falx cerebri and tentorium cerebelli

Diaphragma sellae

Pituitary gland

Sella turcicaof sphenoid

Inferior sagittal sinus

Dura mater

Superior sagittal sinus

Cranium

Falx cerebri

Tentoriumcerebelli

Transversesinus

Falx cerebelli


Figure 16.5a The Cranial Meninges, Part II

Coronal section

This view shows the organization and relationshipof the cranial meninges to the brain.

Arachnoidmater

ArachnoidtrabeculaePia mater

Dura mater

Cerebral cortex

Falx cerebri

Subarachnoidspace

Arachnoidgranulation

Subduralspace

Superior sagittalsinus


Figure 16.5b The Cranial Meninges, Part II

Coronal section

A detailed view of the arachnoid membrane, thesubarachnoid space, and the pia mater. Note therelationship between the cerebral vein and thesubarachnoid space.

Arachnoid mater

Arachnoidtrabecula

Cerebralvein

Perivascularspace

Pia materCerebralcortex



• Cerebrospinal Fluid (CSF)• Provides protection of the brain and spinal cord• Provides support• Transports nutrients to the CNS tissue• Transports waste away from the CNS


Figure 16.6 The Choroid Plexus and Blood–Brain Barrier

INTERSTITIAL FLUID IN THALAMUS

The location of the choroid plexus ineach of the four ventricles of the brain

The structure and function of thechoroid plexus. The ependymalcells are a selective barrier, actively transporting nutrients, vitamins, and ions into the CSF. Whennecessary, these cells also activelyremove ions or compounds fromthe CSF to stabilize its composition. CEREBROSPINAL FLUID IN THIRD VENTRICLE

CHOROID PLEXUS

Tight junction

Ions(Na, K, Cl, HCO3

, Ca2, Mg2)VitaminsOrganic nutrientsOxygen

Waste productsIonsAmino acids(when necessary)

Choroidplexuscells

Capillary

CO2

Waste products

Tightjunction Astrocyte Neuron

Blood–brainbarrier

Capillary

Endothelial cell

Ependymalcells

Nutrients(especially glucose)Oxygen



• Circulation of CSF• CSF from the choroid plexus of the lateral ventricles• Flows through the interventricular foramen• Flows into the third ventricle• Flows into the aqueduct of the midbrain• Flows into the fourth ventricle• Through the lateral aperture and median aperture and

central canal of the spinal cord• Flows into the subarachnoid space• Flows around the brain and spinal cord eventually

enters circulation via the arachnoid granulations


Figure 16.7 Circulation of Cerebrospinal Fluid

Dura mater

Filumterminale

Spinalcord

Centralcanal

Subarachnoid space

Arachnoid mater

Median aperture

Choroid plexus offourth ventricle

Lateral aperture

Aqueductof midbrain

Choroid plexusof third ventricle

Extension of choroidplexus into

lateral ventricle

Arachnoidgranulations

Superiorsagittalsinus

Piamater

Subarachnoidspace

Cerebralcortex

Superiorsagittal sinus Cranium Dura mater

(endosteallayer)

Arachnoidgranulation

Fluidmovement

Arachnoidtrabecula

Dura mater(meningeallayer)

Subdural space

Arachnoidmater


The Medulla Oblongata

• Medulla oblongata • Continuous with the spinal cord to the brain

stem• All communication between the brain and spinal

cord passes through the medulla oblongata


The Medulla Oblongata

• Nuclei of cranial nerves• Contains sensory and motor nuclei of cranial

nerves:• VIII, IX, X, XI, and XII

• Autonomic nuclei• Major centers include:

• Cardiovascular centers (cardiac and vasomotor)• Respiratory centers (rhythmic breathing)


Figure 16.8a The Medulla Oblongata

Anterior view

PyramidsOlive

Medullaoblongata

Pons

Spinal cord

Olivary nucleus

Cardiovascularcenters

Solitary nucleus

Nucleus cuneatus

Nucleus gracilis

Reticular formation

Lateral white column


Figure 16.8b The Medulla Oblongata

PyramidsOlive

Pons

Posterolateral view

Spinal cord

Olivary nucleus

Cardiovascularcenters

Respiratoryrhythmicity center

Solitary nucleus

Nucleus cuneatus

Nucleus gracilis

Reticular formation

Lateral white column

Attachment tomembranousroof of fourthventricle

Posteriormedian sulcus

Posteriorwhite columns


The Pons

• The pons is a prominent bulge superior tothe medulla oblongata and consists of:

• Sensory and motor nuclei for cranial nerves:• V, VI, VII, and VIII

• Nuclei involved with involuntary control of breathing:

• Consist of apneustic center and pneumotaxic center

• Nuclei that relay cerebellar commands:• Consist of cerebellar peduncles


Figure 16.9 The Pons

Olivarynucleus

Medullaoblongata

Transversefibers

Ascendingtracts

Pons

Descending tracts

Pneumotaxiccenter

Apneusticcenter

Cerebellum

Fourthventricle

Reticularformation


The Mesencephalon

• Mesencephalon (also called the midbrain)• Consists of two pairs of nuclei collectively called

corpora quadrigemina• Responsible for processing auditory and visual

stimuli• Auditory processing occurs in the inferior colliculus• Visual processing occurs in the superior colliculus

• Consists of nuclei of the reticular formation• Involved in maintaining alertness


The Mesencephalon

• Mesencephalon (continued)• Consists of:

• Red nucleus: integrates information between the cerebrum and cerebellum

• Substantia nigra: regulates motor output of the basal nuclei

• Cerebral peduncles: have ascending fibers that synapse in the thalamus and descending fibers of the corticospinal pathway


Figure 16.10b The Mesencephalon

Diagrammatic and posterior views of the diencephalonand brain stem. The diagrammatic view is drawn, as iftransparent, to show the positions of important nuclei.

Superiorcolliculi

Inferiorcolliculi

Corporaquadrigemina

Trochlearnerve (N IV)

Cerebralpeduncle

Superiorcerebellarpeduncle

Reticular formationin floor of

fourth ventricle

Fourth ventricle

Pinealgland

Superiorcolliculus

Cerebralpeduncle

Thalamus

Red nucleus

Substantianigra

Inferiorcolliculus

Reticular formation


The Diencephalon

• The diencephalon consists of:• Epithalamus• Thalamus • Hypothalamus


Figure 16.12a The Hypothalamus

Midsagittal section through the brain. This view shows the major featuresof the diencephalon and adjacent portions of the brain stem.

Opticnerve

Infundibulum(cut)

Tuberalarea

Mamillarybody

Corpuscallosum

Septumpellucidum

Fornix

Anteriorcerebral artery

Frontal lobe

Anteriorcommissure

Optic chiasm

Parietallobe

Choroid plexusin epithalamus

Thalamus(surroundsthird ventricle)

Pineal gland

Aqueduct ofmidbrain

Hypothalamus

Cerebellum

Fourthventricle


The Diencephalon

• The epithalamus• Forms the roof of the third ventricle• Contains the pineal gland

• Produces the hormone melatonin• Regulates our day/night cycles


The Diencephalon

• The thalamus• Forms the walls of the third ventricle


Figure 16.11a The Thalamus

Lateral view of the brain showing thepositions of the major thalamicstructures. Functional areas of cerebral cortex are also indicated,with colors corresponding to those ofthe associated thalamic nuclei.

Occipitallobe

Parietal lobeFrontallobe


Figure 16.11b The Thalamus

Enlarged view of the thalamic nuclei of the left side. The color ofeach nucleus or group of nuclei matches the color of the associatedcortical region. The boxes either provide examples of the types ofsensory input relayed to the basal nuclei and cerebral cortex orindicate the existence of important feedback loops involved withemotional states, learning, and memory.

Cerebellum

Basalnuclei

Generalsensory

inputVisualinput

Auditoryinput

Limbicsystem

Frontallobes

Parietal lobe andcingulate gyrus

Association areasof cerebral cortex

Lateralgeniculatenucleus

Medialgeniculatenucleus

Pulvinar

Medial group

Lateral group

Anterior group

Posteriorgroup

V e n t r a lg r o u p


The Diencephalon

• The hypothalamus• Forms the floor of the third ventricle• Consists of numerous nuclei• Consists of an infundibulum, which connects

to the pituitary gland


The Diencephalon

• The hypothalamus (continued)• Consists of nuclei to control:

• Subconscious control of skeletal muscles• Heart rate, blood pressure, respiration, and digestive

functions• Secretion of antidiuretic hormone and oxytocin• Emotional and behavioral drives and thirst drives• Coordination between voluntary and autonomic

functions• Body temperature• Circadian rhythm


Figure 16.12a The Hypothalamus

Midsagittal section through the brain. This view shows the major featuresof the diencephalon and adjacent portions of the brain stem.

Opticnerve

Infundibulum(cut)

Tuberalarea

Mamillarybody

Corpuscallosum

Septumpellucidum

Fornix

Anteriorcerebral artery

Frontal lobe

Anteriorcommissure

Optic chiasm

Parietallobe

Choroid plexusin epithalamus

Thalamus(surroundsthird ventricle)

Pineal gland

Aqueduct ofmidbrain

Hypothalamus

Cerebellum

Fourthventricle


Figure 16.12b The Hypothalamus

Enlarged view of the hypothalamus showing the locations of major nuclei andcenters. Functions for these centers are summarized in Table 16.6.

Thalamus

Hypothalamus

Pons

Tuberalarea

Mamillarybody

Posterior lobe ofpituitary gland(pars nervosa)

Autonomic centers(sympathetic)

Paraventricularnucleus

Preoptic area

Autonomic centers(parasympathetic)

Suprachiasmaticnucleus

Anteriorlobe of

pituitarygland

Supraoptic nucleus

Tuberal nuclei

Optic chiasm

Infundibulum

Pars distalis

Pars intermedia


The Cerebellum

• The cerebellum consists of:• Two hemispheres• Folia (folds similar to gyri of the cerebrum)• Anterior and posterior lobes• Vermis (separates the hemispheres)• Flocculonodular lobes• Arbor vitae• Cerebellar peduncles


Figure 16.15b The Cerebellum

Dendrites projectinginto the gray matter

of the cerebellum

Axons of Purkinje cellsprojecting into the whitematter of the cerebellum Purkinje cells LM 120

Cell body of Purkinje cell

Sagittal view of the cerebellum showing the arrangement of gray matterand white matter. Purkinje cells are seen in the photomicrograph; theselarge neurons are found in the cerebellar cortex.

Cerebellarpeduncles

SuperiorMiddle

Inferior

Medulla oblongata

Pons

Anterior lobe

Arborvitae

Cerebellarnucleus

Cerebellarcortex

Posterior lobe

Flocculonodular lobe

Choroid plexus ofthe fourth ventricle

Medullaoblongata

Fourthventricle

Mamillarybody

Pons

Superior colliculus

Aqueduct of midbrain

Inferior colliculus

Anterior lobe

Arbor vitae

Cerebellar cortex

Cerebellarnucleus

Posteriorlobe

Flocculonodular lobe

Mesencephalon


Figure 16.15a The Cerebellum

Superior surface of the cerebellum. This viewshows major anatomical landmarks and regions.

Left hemisphereof cerebellum

Right hemisphereof cerebellum

Folia

Folia

Vermis Vermis

Cerebellum

Anterior lobe

Primary fissure

Posterior lobe


The Cerebellum

• The cerebellum• Cerebellar cortex: subconscious coordination

of movements• Arbor vitae: connects cerebellar cortex with

cerebellar peduncles


The Cerebrum

• The cerebrum consists of:• Two hemispheres• Several lobes

• Frontal, parietal, occipital, and temporal

• Gyri and sulci• Longitudinal fissure• Corpus callosum• Basal nuclei• Limbic system


The Cerebrum

The cerebrum is the largest, most superior portion of the human brain. Each cerebral hemisphere receives sensory information from and generates motor commands to the opposite side of the body. The two hemispheres have some functional differences, although anatomically they appear to be identical. The cerebral hemispheres are separated by longitudinal fissure.Cortical surface of the brain forms a series of grooves called sulci.

The sulcus between frontal and parietal lobe is central sulcus. This sulcus functionally separates the sensory and motor part of cerebrum.The sulcus between parietal and temporal lobe id lateral sulcus.The eminence between two sulsi is called gyrus.


Figure 16.16a The Cerebral Hemispheres, Part I

Superior view

POSTERIOR

ANTERIOR

Right cerebralhemisphere

Cerebral veins andarteries covered byarachnoid mater

Central sulcus


Cerebellum


Longitudinalfissure


The Cerebrum

• The Cerebral Hemispheres• The Cerebral Lobes

• Frontal lobe: conscious control of skeletal muscles• Occipital lobe: perception of visual stimuli• Parietal lobe: conscious perception of touch,

pressure, vibration, pain, temperature, and taste• Temporal lobe: conscious perception of auditory and

olfactory stimuli


Figure 16.17a The Cerebral Hemispheres, Part II

Lateral view of intact brain after removal of thedura mater and arachnoid mater showingsuperficial surface anatomy of the left hemisphere

Precentral gyrus

Central sulcus

Lateral sulcus

FRONTAL LOBEof left cerebral

hemisphere

Branches of middlecerebral artery emerging

from lateral sulcus

TEMPORAL LOBE

Medulla oblongata

Pons

Cerebellum

OCCIPITAL LOBE

PARIETAL LOBE

Postcentralgyrus


Figure 16.13a Sectional Views of the Brain

MesencephalonPons

Temporal lobe

Mamillary body

Optic chiasm

Anteriorcommissure

Frontal lobe


Septumpellucidum

Corpus callosum

Precentral gyrus Central sulcus Postcentral gyrusCingulate gyrus

FornixThalamus

Membranous portionof epithalamusHypothalamus

Pineal gland


Superiorcolliculus

CorporaquadrigeminaInferior

colliculus

Aqueductof midbrain

Fourth ventricle

Cerebellum

Medullaoblongata

A sagittal section through the brain


The Cerebrum

• Hemispheric Specialization• Left hemisphere

• Speech center, writing, language, mathematics

• Right hemisphere• Analysis by touch, spatial visualization


Figure 16.18 Hemispheric Specialization

LEFT HAND

Prefrontalcortex

Speech center

Writing

Auditory cortex(right ear)

General interpretivecenter (language

and mathematicalcalculation)

Visual cortex(right visual field)

LEFTHEMISPHERE

RIGHTHEMISPHERE

CORPUS

CALLOSUM

RIGHT HAND

Prefrontalcortex

Anterior commissure

Auditory cortex(left ear)

Analysisby touch

Spatialvisualizationand analysis

Visual cortex(left visual field)


The Cerebrum

• The Central White Matter• Consists of bundles called:

• Association fibers: tracts that interconnect areas of neural cortex within a hemisphere (arcuate fibers and longitudinal fasciculi)

• Commissural fibers: tracts that connect the two hemispheres (anterior commissure and corpus callosum)

• Projection fibers: tracts that link the cerebrum with other regions of the brain and spinal cord


Figure 16.19a The Central White Matter

Lateral aspect of the brain showingarcuate fibers and longitudinal fasciculi

Arcuate fibers

Longitudinalfasciculi


Figure 16.19b The Central White Matter

Anterior view of the brain showing orientationof the commissural and projection fibers

Anterior commissure

Projection fibers ofinternal capsule

Corpuscallosum

Longitudinalfissure


The Cerebrum

• The Basal Nuclei• These are masses of gray matter embedded in

the white matter inferior to the lateral ventricles• Consist of:

• Caudate nucleus• Putamen• Globus pallidus• Claustrum• Amygdaloid body


The Cerebrum

• The Basal Nuclei• Caudate nucleus, putamen, and globus

pallidus• Control the cycles of arm and leg movements when

walking

• Claustrum• Plays a role in subconscious processing of visual

information. It focuses attention on specific patterns or relevant features (watching movie!)

• Amygdaloid body• Component of the limbic system


Figure 16.20c The Basal Nuclei

Frontal section

Head of caudatenucleus

Lateralventricle

Claustrum

Insula

Putamen

Lentiformnucleus

Globuspallidus

Amygdaloid body

Corpus callosum

Septum pellucidum

Internal capsule

Lateral sulcus

Anterior commissure

Tip of inferior horn oflateral ventricle


The Cerebrum

• The Limbic System• Located between the cerebrum and the

diencephalon just superior to the corpus callosum

• Functions:• Establishes emotional states• Links the conscious functions with the unconscious

autonomic functions• Facilitates memory storage and retrieval


Figure 16.21a The Limbic System

Sagittal section through the cerebrum showing the corticalareas associated with the limbic system. The parahippocampaland dentate gyri are shown as if transparent so that deeperlimbic components can be seen.

ThalamusHypothalamus

Temporal lobe

Parahippocampalgyrus (limbic lobe) Hippocampus

(within dentate gyrus)Mamillary

body

Corpuscallosum

Interthalamicadhesion

Centralsulcus

Cingulate gyrus(limbic lobe)

Fornix

Pineal gland


The Cerebrum

• The Limbic System• The fornix

• Tract of white matter connecting the hippocampus with the hypothalamus

• Many fornix fibers extend to the mamillary bodies• Mamillary bodies control reflex movements

associated with eating


The Cranial Nerves

• There are 12 pairs of cranial nerves• These nerves innervate the periphery emerging

from the brain (not the spinal cord)• These nerves are on the ventrolateral surface of

the brain• They are numbered beginning at the anterior

aspect of the brain• They are numbered CN I to CN XII


Figure 16.22b Origins of the Cranial Nerves

Diagrammatic inferior view of the humanbrain. Compare view with part (a).

Olfactory bulb, terminationof olfactory nerve (N I)

Olfactory tract

Optic chiasm

Optic nerve (N II)

Infundibulum

Oculomotor nerve (N III)

Trochlear nerve (N IV)

Trigeminal nerve (N V)

Abducens nerve (N VI)

Facial nerve (N VII)

Vestibulocochlearnerve (N VIII)

Glossopharyngealnerve (N IX)

Vagus nerve (N X)

Hypoglossal nerve (N XII)

Accessory nerve (N XI)


The Cranial Nerves

• CN I: The Olfactory Nerve• Function: sensory (smell)• Origin: olfactory epithelium• Foramen: olfactory foramina• Destination: olfactory bulbs


Figure 16.23 The Olfactory Nerve

Olfactorynerve fibers

Olfactory epithelium

Cribriform plateof ethmoid

OLFACTORYNERVE (N I)

Olfactory tract(to olfactory cortex

of cerebrum)

Left olfactory bulb(termination of

olfactory nerve)


The Cranial Nerves

• CN II: The Optic Nerve• Function: sensory (vision)• Origin: retina • Foramen: optic canal• Destination: diencephalon, then to occipital

lobe


Figure 16.24 The Optic Nerve

OPTIC NERVE(N II)

Mesencephalon(cut)

Optic chiasm

Optic tract

Eye

Visual cortex(in occipital lobes)

Opticprojectionfibers

Lateralgeniculatenucleus(in thalamus)

Pituitarygland

Olfactory tract

Olfactory bulb


The Cranial Nerves

• CN III: The Oculomotor Nerve• Function: controls extra-ocular eye muscles

• Motor function• Superior, inferior, and medial rectus• Inferior oblique• Levator palpebrae superioris

• Origin: mesencephalon• Foramen: superior orbital fissure• Destination: extra-ocular eye muscles


Figure 16.25 Cranial Nerves Controlling the Extra–Ocular Muscles

Trigeminalnerve (N V), cut

Vestibulocochlearnerve (N VIII), cut

Facial nerve(N VII), cut

ABDUCENSNERVE (N VI)

Lateralrectusmuscle

(cut)

Medialrectusmuscle

Inferiorrectusmuscle

Ciliaryganglion

OPTICNERVE (N II)

Opticchiasm

OCULOMOTORNERVE (N III)

TROCHLEARNERVE (N IV)

SuperiorrectusmuscleSuperior

obliquemuscle

Trochlea

Levatorpalpebraesuperioris

muscle

Inferiorobliquemuscle


The Cranial Nerves

• CN IV: The Trochlear Nerve• Function: controls extra-ocular eye muscles

• Motor function• Superior oblique

• Origin: mesencephalon• Foramen: superior orbital fissure• Destination: extra-ocular eye muscles







Lateralrectusmuscle

(cut)

Medialrectusmuscle


Ciliaryganglion

OPTICNERVE (N II)

Opticchiasm




obliquemuscle

Trochlea


muscle



The Cranial Nerves

• CN V: The Trigeminal Nerve• Function:

• Mixed (sensory and motor) function• Ophthalmic: sensations from the forehead, eyelids,

and nose• Maxillary: sensations from lower eyelid, upper lip, and

cheek• Mandibular: controls mastication

• Origin: ophthalmic, maxillary, and mandibular nerves


The Cranial Nerves

• CN V: The Trigeminal Nerve (continued)• Foramen:

• Ophthalmic: superior orbital fissure• Maxillary: foramen rotundum• Mandibular: foramen ovale

• Destination: • Ophthalmic and maxillary: Pons• Mandibular: mandibular muscles


Figure 16.26 The Trigeminal Nerve

TRIGEMINALNERVE (N V)

Maxillarybranch

Foramen ovale

Pons

Otic ganglion

Mandibular branch

Pterygopalatineganglion

Ophthalmicbranch

Semilunarganglion

Superiororbitalfissure

Supraorbitalnerves

Ciliary ganglion

Foramenrotundum

Infra-orbitalnerve

Lingual nerve

Submandibular ganglion

Mental nerve


The Cranial Nerves

• CN VI: The Abducens Nerve • Function: controls eye movements

• Motor function

• Origin: pons• Foramen: superior orbital fissure• Destination: innervates the lateral rectus eye

muscle







Lateralrectusmuscle

(cut)

Medialrectusmuscle


Ciliaryganglion

OPTICNERVE (N II)

Opticchiasm




obliquemuscle

Trochlea


muscle



The Cranial Nerves

• CN VII: The Facial Nerve • Function: Mixed (sensory and motor)

• Sensory: sensations from the face / taste • Motor: controls muscles of the face

• Origin: • Sensory: taste buds• Motor: pons

• Foramen: internal acoustic meatus• Destination:

• Sensory: pons• Motor: muscles of the face


Figure 16.27a The Facial Nerve

Origin and branches of the facialnerve

Posterior auricularbranch

Stylomastoidforamen

Chorda tympani nerve(with mandibularbranch of N V)

Lingual branch(with lingual nerveof N V)

Submandibular ganglion

Pons

Pterygopalatineganglion

Greaterpetrosal

nerve

Geniculateganglion

FACIALNERVE (N VII)

Temporalbranch

Zygomaticbranches

Buccalbranch

Mandibularbranch

Cervicalbranch


The Cranial Nerves

• CN VIII: The Vestibulocochlear Nerve • Function:

• Sensory: balance and hearing

• Origin: receptors of the vestibule and cochlea• Foramen: internal acoustic meatus• Destination: pons


Figure 16.28 The Vestibulocochlear Nerve

Tympaniccavity

(middle ear)Semicircular

canals

Vestibularbranch(N VIII)

Facialnerve

(N VII), cut

Internalacoustic

canalVESTIBULOCOCHLEAR

NERVE (N VIII)

Pons

N V

N VIN VII

N IXN XIIN X

N XI

Medullaoblongata

Cochlearbranch (N VIII)

CochleaAuditorytube

Tympanicmembrane


The Cranial Nerves

• CN IX: The Glossopharyngeal Nerve • Function: Mixed (sensory and motor)

• Sensory function: taste of posterior 1/3 of tongue.• Motor function: swallowing

• Origin: • Sensory: posterior 1/3 of the tongue• Motor: salivary gland


The Cranial Nerves

• CN IX: The Glossopharyngeal Nerve (continued)

• Foramen: jugular foramen• Destination:

• Sensory: pons• Visceral motor: parotid salivary gland• Somatic motor: pharyngeal muscles for swallowing


Figure 16.29 The Glossopharyngeal Nerve

Common carotid artery

Carotid sinus

Carotid body

Lingual branch

Otic ganglion

Inferior (petrosal)ganglion

GLOSSOPHARYNGEALNERVE (N IX)

Superior (jugular)ganglion

Pharyngeal branches

Carotid sinusbranch

Parotid salivarygland

Medulla oblongata

Pons

N VII

N VI

N V

N VIII


The Cranial Nerves

• CN X: The Vagus Nerve • Function:

• Sensory: information from organs• Motor: sends information to the organs

• Origin: • Sensory: from the organs• Motor: medulla oblongata


The Cranial Nerves

• CN X: The Vagus Nerve (continued) • Foramen: jugular foramen• Destination:

• Sensory: autonomic centers of the medulla oblongata• Somatic motor: muscles of the palate and pharynx• Visceral motor: respiratory, cardiovascular, and

digestive organs


Figure 16.30 The Vagus Nerve

Superiorpharyngeal

branch

Superiorlaryngeal nerve

Recurrentlaryngeal nerve

Internal branch

External branch

VAGUSNERVE (N X)

Inferiorganglion of

vagus nerve

Cardiac branches

Cardiac plexus

Anteriorvagal trunk

Left lungRight lung

Liver

Stomach

Colon

Pancreas

Spleen

Small intestine

Celiacplexus

Hypogastricplexus

Medulla oblongata

Auricular branchto external ear

Superior ganglionof vagus nerve

Pharyngeal branch

Superior laryngeal nerve


The Cranial Nerves

• CN XI: The Accessory Nerve • Function:

• Motor: controls the sternocleidomastoid, trapezius, palate, pharynx, and larynx muscles

• Origin: spinal cord and medulla oblongata • Foramen: jugular foramen• Destination:

• Internal branch: muscles of the palate, pharynx, and larynx

• External branch: sternocleidomastoid and trapezius muscles


Figure 16.31 The Accessory and Hypoglossal Nerves

HYPOGLOSSAL NERVE (N XII)

ACCESSORY NERVE (N XI)

Internal branch: to palatal,pharyngeal, and laryngealmuscles with vagus nerve

Intrinsic musclesof tongue

Styloglossus muscle

Genioglossus muscle

Geniohyoid muscle

Hyoglossus muscle

Hyoid bone

Thyrohyoid muscle

Sternohyoid muscle

Sternothyroid muscle

Omohyoid muscle

Sternocleidomastoid muscle

Trapezius muscle

Ansa cervicalis(cervical plexus)

Spinal cord

External branch of N XI

Spinal root of N XI

Cranial root of N XI


Medulla oblongata


The Cranial Nerves

• CN XII: The Hypoglossal Nerve • Function:

• Motor: controls tongue movement

• Origin: medulla oblongata • Foramen: hypoglossal canal• Destination: tongue muscles


Figure 16.31 The Accessory and Hypoglossal Nerves

HYPOGLOSSAL NERVE (N XII)

ACCESSORY NERVE (N XI)

Internal branch: to palatal,pharyngeal, and laryngealmuscles with vagus nerve

Intrinsic musclesof tongue

Styloglossus muscle

Genioglossus muscle

Geniohyoid muscle

Hyoglossus muscle

Hyoid bone

Thyrohyoid muscle

Sternohyoid muscle

Sternothyroid muscle

Omohyoid muscle

Sternocleidomastoid muscle

Trapezius muscle

Ansa cervicalis(cervical plexus)

Spinal cord

External branch of N XI

Spinal root of N XI

Cranial root of N XI


Medulla oblongata


The Cranial Nerves

• Summary of Cranial Nerve Branches and Functions

• Mnemonic aid• Oh, Once One Takes The Anatomy Final, Very Good

Vacations Are Heavenly


Table 16.12 The Cranial Nerves (Part 1 of 2)


Table 16.12 The Cranial Nerves (Part 2 of 2)

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