Neuro9 Cranial Nerves

Question 1

Cranial nerve nuclei

Answer 1

Located in tegmentum portion of brain stem (between dorsal and ventral portions) .

Lateral nuclei = sensory (alar plate). - Sulcus limitans-

Question 2

Midbrain

Answer 2

nuclei of CN III, I V

Question 3

Pons

Answer 3

nuclei of CN V, VI, V II, VIII

Question 4

Medulla

Answer 4

nuclei of CN IX, X, XII

Question 5

Corneal Cranial nerve reflex

Answer 5

Afferent:
V1 ophthalmic (nasociliary branch)

Efferent:
VII (temporal branch: orbicularis oculi)

Question 6

Lacrimation Cranial nerve reflex

Answer 6

V 1 (loss of reflex does not preclude emotional tears)

VII

Question 7

Jaw jerk Cranial nerve reflex

Answer 7

V3 (sensory-muscle spindle from masseter)

V3 (motor-masseter)

Question 8

Pupillary reflex

Answer 8

Afferent: II

Efferent: III

Question 9

Gag

Answer 9

Afferent: IX

Efferent: IX, X

Question 10

Vagal nuclei: Nucleus Solitarius

Answer 10

Visceral Sensory information (e.g., taste,
baroreceptors, gut distention).

VII, IX, X.

Question 11

Vagal nuclei: Nucleus aMbiguus

Answer 11

Motor innervation of pharynx, larynx, and upper esophagus (e.g., swallowing, palate elevation) .

IX, X, XI.

Question 12

Vagal nuclei:Dorsal motor nucleus

Answer 12

Sends autonomic (parasympathetic) fibers to heart, lungs, and upper GI.

Question 13

Cranial nerve and

vessel pathways

Answer 13

Cribriform plate (CN 1).
Middle cranial fossa (CN II-VI) -through
sphenoid bone:
l . Optic canal (CN II, ophthalmic artery,
central retinal vein)
2. Superior orbital fissure (CN III, IV, V1,
VI, ophthalmic vein, sympathetic fibers)
3. Foramen Rotundum (CN V2)
4. Foramen Ovale (CN V3)
5. Foramen spinosum (middle meningeal
artery)
Posterior cranial fossa (CN VII-XII) - through
temporal or occipital bone :
I. Internal auditory meatus (CN VII, VIII)
2. Jugular foramen (CN IX, X, XI, jugular
vein)
3. Hypoglossal canal (CN XII)
4. Foramen magnum (spinal roots of CN
XI, brain stem, vertebral arteries)

Divisions of CN V exit owing to Standing Room
Only.

Question 14

Cavernous sinus

Answer 14

A collection o f venous sinuses o n either side of
the pituitary. Blood from eye and superficial
cortex goes to cavernous sinus goes to internal jugular
vein.

CN III, IV, V1, V2, and VI and postganglionic
sympathetic fibers en route to the orbit all
pass through the cavernous sinus. Cavernous
portion of internal carotid artery is also here.

The nerves that control extraocular muscles
(plus V1 and V2) pass through the cavernous
sinus.

Cavernous sinus syndrome (e.g., due to mass
effect) - ophthalmoplegia, ophthalmic and
maxillary sensory loss.

Question 15

CN XII lesion (LMN)

Answer 15

tongue deviates toward side of lesion (lick your wounds) due to weakened tongue muscles on the affected side

Question 16

CN V motor lesion

Answer 16

jaw deviates toward side of lesion due to unopposed force from the opposite pterygoid muscle.

Question 17

CN X lesion

Answer 17

uvula deviates away from side of lesion. Weak side collapses and uvula points away

Question 18

CN XI lesion

Answer 18

weakness turning head to contralateral side of lesion (SCM). Shoulder droop on side of lesion (trapezius)

Question 19

Conductive hearing loss

Answer 19

abnormal Rinne test (bone > air); Weber test localizes to affected ear

Question 20

Sensorineural hearing loss

Answer 20

normal Rinne test (air > bone); Weber test localizes to unaffected ear.

Question 21

Facial Nerve UMN lesion

Answer 21

Lesion of motor cortex or connection between cortex and facial nucleus. Contralateral paralysis of lower face only, since upper face receives bilateral UMN innervation.

Question 22

Facial Nerve LMN lesion

Answer 22

Ipsilateral paralysis of upper and lower face.

Question 23

Bell’s palsy

Answer 23

Complete destruction of the facial nucleus itself
or its branchial efferent fibers (facial nerve
proper) .
Peripheral ipsilateral facial paralysis with
inability to close eye on involved side.
Can occur idiopathically; gradual recovery in
most cases.
Seen as a complication in AIDS, Lyme disease,
Herpes simplex, Sarcoidosis, Tumors, Diabetes
(Alexander graHam Bell with STD) .

Question 24

Mastication muscles

Answer 24

3 muscles close jaw: Masseter, teMporalis,
Medial pterygoid. 1 opens: lateral pterygoid.
All are innervated by the trigeminal nerve
(V3).