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The Cranial Nerves and Cranial Nerve Nuclei

of the Brain Stem

Objectives:

Learn the name and numerical designation of each of the twelve cranial nerves

Learn the names and functions of the cranial nerve nuclei of the brain stem and the nerves that arise or terminate in each of these nuclei

Learn the location of each of the cranialnerve nuclei of the brain stem on thebrain stem model

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12 pairs of Cranial Nerves arise from the forebrain and the brain stem.

I Olfactory Telencephalon II Optic Diencephalon

Cranial Nerves III through XII arise from the Brain Stem:Midbrain III Oculomotor IV TrochlearPons V Trigeminal VI Abducens VII FacialMedulla VIII Vestibulocochlear IX Glossopharyngeal X Vagus XII Hypoglossal

Cranial Nerve XI - Spinal Accessory Nerve arises from the Spinal Cord

III III

IVVI

V

VII

VIII

IX

XXIXII

Drawing A shows the ventral surface of a model of a dissected human brain. The cerebral cortex with its underlying white matter and the cerebellum have been removed. In the forebrain the caudate (c) and putamen (p) join together in the anterior, ventral area of the basal ganglia.

Cranial nerves:

OPTIC II

OCULOMOTOR III TROCHLEAR IV TRIGEMINAL V ABDUCENS VI FACIAL VII

VESTIBULOCOCHLEAR VIII GLOSSOPHARYNGEAL IX VAGUS X HYPOGLOSSAL ROOTLETS XII

SPINAL ACCESSORY XI

cp

Only the trochlear nerve IVarises from the dorsal surface of the brain stem.It courses around themidbrain to join III and VI to enter the orbit.

A

B dorsal view

c

thmidbrain

pons

medulla

spinal cord

3

4

Cranial Nerve Nuclei

The cranial nerves innervate thehead and neck,

Cranial nerve fibers include the samefour “general” functional components as the spinal nerves :GSE, GVE, GVA and GSA.

In addition the head contains 1) “special” visceral sensory organs for olfaction and taste,2) “special” somatic sensory organs for vision, audition, and balance, and 3) a “special” group of muscles embryologically derivedfrom the branchial arches.

Thus seven functionally-distinct columns of cells in the brain stem comprise the cranial nerve nuclei:

GSE somatic motorGVE preganglionic parasympatheticSVE branchial motorGVA visceral sensorySVA olfaction and tasteGSA somatosensorySSA audition and vestibular function

The model showsa “dissection” of thecranial nerve nucleiin the tegmentum ofthe brain stem.

4

5

GSE SOMATIC MOTOR oculomotor III trochlear IV abducens VI hypoglossal XII tongue mm.

GVE PARASYMPATHETIC Edinger Westphal III (not on model) salivatory nuclei VII, IX dorsal motor nucleus of X

SVE BRANCHIOMOTOR motor nuc. V mastication facial nuc. VII facial expression nucleus ambiguus IX, X, cXI pharynx, larynx accessory sXI trapezius, sternomastoid

IV

III

VI

XII

V

VII

sXI

MOTOR NULCEI

VIIIX

extraocular mm.

X

Nucleus ambiguusIX, X and cXI

5

6

VIII vestibular

VIII cochlear

rost nuc solitarius VII, IX, Xcaud nuc solitarius IX, X

V principal sensory

SENSORY NULCEI

SSA AUDITION AND BALANCE vestibular VIII cochlear VIII

GSA SOMATOSENSORY trigeminal V: mesencephalic proprioception principal sensory discriminative touch spinal pain & temperature

SVA TASTE nucleus solitarius, rostral VII, IX, X GVA PAIN, etc. nucleus solitarius caudal IX, X

V spinal

V mesencehaplic

6

7

A

B

C

D

E

F

G

H

Match each cranial nerve nucleus (A - H) with theappropriate functional designation (1 - 8).

_____ 1. receives pain input from teeth

_____ 2. innervates pharyngeal mm. _____ 3. receives input from inner ear

_____ 4. Innervates tongue mm.

_____ 5. receives fine tactile input from lips _____ 6. Innervates mm. of mastication

_____ 7. preganglionic parasympathetic

_____ 8. Innervates extraocular mm.

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Cranial Nerves and

Cranial Nerve Nuclei of the Brain Stem

Question I

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Cranial Nerves and Cranial Nerve Nuclei of the Brain StemANSWER SHEET

Question I

1. E2. D3. C4. I5. B6. G7. H8. F