CN nuclei and lesions

Question 1

Vagal nuclei:

Nucleus solitarius

Answer 1

Solitarius=Sensory
Visceral sensory info; taste, baroceptor, gut distension

CN 7, 9, 10

Question 2

Vagal nuclei:

Nucleus aMbiguus

Answer 2

aMbiguus=Motor
Motor innervation of pharynx, larynx, and upper esophagus
(swallowing, palate elevation)

CN 9, 10
Affected in PICA
“Don’t pick a horse that can’t swallow”

Question 3

Vagal nuclei:

Dorsal motor nucleus

Answer 3

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

CN 10 only

Question 4

Cranial nerve and vessel pathways:

Cribriform plate

Answer 4

CN1

Question 5

Cranial nerve and vessel pathways:

Middle cranial fossa

Answer 5

CN 2-6, via sphenoid bone

Optic canal: CN2, opthalmic atery, central retinal vein

Superior ortital fissure: CN3, 4,5-1 (opht), 6, opthalmic vein, sympathetic fibers

Foramen rotundum: CN5-2 (max)

Foramen ovale: CN5-3 (mandible)

Foramen spinosum: middle meningeal artery

Question 6

Cranial nerve and vessel pathways:

Posterior cranial fossa

Answer 6

CN 7-12, through temporal and occipital bone

Internal auditory meatus: CN 7,8

Jugular foramen: CN 9, 10, 11, jugular vein

Hypoglossal canal: CN 12

Foramen magnum: spinal root of CN 11, brain stem, vertebral artery.

Question 7

Cavernous sinus

Answer 7

Collection of venous sinuses on either side of the pit.
Blood from eye and superficial cortex -> cavernous sinus -> internal jugular vein

CN3, 4, 5-1 and 5-2 and 6, 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 muscules (5-1 and 5-2) pass through the cavernous sinus

Question 8

Cavernous sinus syndrome

Answer 8

Due to pass effect, fistula, thrombosis

Ophthalmoplegia and reduced corneal and maxillary sensation with normal vision.

Question 9

CN 5 motor lesion

Answer 9

Jaw deviates TOWARD the side of lesion toward unopposed force from the opposite pterygoid muscle

JaW toWard

Question 10

CN 10 lesion

Answer 10

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

UvulAAA Awayyyy

Question 11

CN 11 lesion

Answer 11

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

The left SCM contracts to help turn the head to the right

Question 12

CN 12 (LMN)

Answer 12

Tongue deviates TOWARD the side of lesion (lick your wound) due to weakened tongue muscle on the affected side.

Tongue deviates Toward

Question 13

Hearing loss: conductive

Answer 13

Renne test: abnormal (bone> air)
Weber test: localizes to affected ear
(Weber: better heard on the affected ear, because denser stuff in the ear conducts air-mass interface higher)

Question 14

Hearing loss: sensorineural

Answer 14

Renne test: normal (air>bone)
Weber test: localizes to unaffected ear
(Weber: better heard on the other ear)

Question 15

Hearing loss: noise-induced

Answer 15

Damage to stereocilliated cells in organ of Corti
Loss of high frequency hearing 1st
Sudden extremely loud noises can produce hearing loss due to tympanic membrane rupture.

Question 16

Facial lesions:

UMN lesions

Answer 16

Lesions of motor cortex or connection between cortex and facial nucleus

Contralateral paralysis of lower face; forehead spared due to bilaterally UMN innervation

Question 17

Facial lesions:

LMN lesions

Answer 17

Ipsilateral paralysis of UPPER AND LOWER face

Question 18

Facial lesions:

Facial nerve palsy

Answer 18

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, HSV or less commonly VZV, sarcoidosis, tumor and diabetes.

Called Bell’s Palsy when idiopathic

Question 19

Mastication muscle

Answer 19

Three muscles close jaw:
Massecter, teMporalis, Medial pterygoid

1 opens: lateral pterygoid.
“Lateral lowers (when speaking of pterygoids with respect to jaw motion)”

All are innervated by the trigeminal nerve (V3)
“M’3 munch”

“It takes more muscle to keep your mouth shut”