Cranial Nerves

Question 1

CN I

Answer 1

olfactory
function = olfaction
testing = ask pt to close one nostril and ask if they can identify test
clinical = anosmia (olfactory loss)

Question 2

CN II

Answer 2

optic
function = vision
testing = snellen eye chart, smallest line they can read; visual field, cover one use and move in and out of line of sight; pupillary light reflex, swinging flashlight test look at symmetry
clinical = corticol blindness (transient or permanent), hallucinations, contralateral homonymous hemianopia

Question 3

CN III

Answer 3

oculomotor
function = eye movements; pupil constriction
testing = hold object in front of patient and ask them to track a moving target, move in all 4 quadrants; convergence
clinical = ptosis (droopy eyelid); oculomotor nerve palsy (unilateral); lesion can lead to lifelong impairment of normal vision

Question 4

CN IV

Answer 4

trochlear
function = eye movements
testing = H test “down and it towards nose”
clinical = trochlear nerve/4th nerve palsy, diplopia, cannot look down and towards your nose, superior oblique muscle affected

Question 5

CN V

Answer 5

trigeminal
function = facial sensation; muscles of mastication
testing = facial sensation; masseter, temporalis, lat/med pterygoid muscles
clinical = loss of sensation in the face (anesthesia or hypoesthesia), weakness or atrophy of the muscles of mastication, difficulty chewing or biting, jaw deviation towards the affected side during mouth opening

Question 6

CN VI

Answer 6

abducens
function = eye movement
testing = hold a pen a finger away from pt moving in H shape pattern pausing during vertical & lateral gaze
clinical = pt will have inability to abduct to the affected side, sixth nerve palsy

Question 7

CN VII

Answer 7

facial
function = muscle of facial expression; taste; lacrimation; salivation
testing = motor, frontalis, orbicularis orbis, buccinator; sensory, cotton swab dipped in sweet, salty, or bitter have them decide on taste before they pull back their tongue
clinical = complete paralysis of all the facial muscles on the ipsilateral side, presents with mouth drop, flattening of the nasolabial fold, inability to close eyes

Question 8

CN VIII

Answer 8

vestibulocochlear
function = hearing; equilibrium sense
testing = rinne test, tuning fork on mastoid process; weber test, tuning fork in middle of forehead; vestibular assessment, observe pt eyes for nystagmus
clinical = LOB, nystagmus, sensorineural hearing loss

Question 9

CN IX

Answer 9

glossopharyngeal
function = pharyngeal muscles; carotid body reflexes; salivation
testing = gag reflex
clinical = contralateral uvula deviation, unilateral hyposalivation, dysphagia, dysphoria, change in taste

Question 10

CN X

Answer 10

vagus
function = parasympathetics to most organs; laryngeal muscles (voice); pharyngeal muscles (swallowing); aortic arch reflexes
testing = ahhh, or kahhh, palate should rise symmetrically, gag reflex
clinical = unilateral weakness the uvula will deviate toward the normal side; bilateral weakness neither side of the palate will elevate; lateral medullary syndrome

Question 11

CN XI

Answer 11

spinal accessory
function = head turning (trapezius and sternomastoid muscles)
testing = shrug their shoulders against resistance
clinical = sternocleidomastoid with be unable to laterally flex, accessory nerve palsy: paralysis of trapezius & STM

Question 12

CN XII

Answer 12

hypoglossal nerve
function = tongue movement
testing = protrude tongue and move side to side, listen to articulations with T & D sounds
clinical = hypoglossal nerve palsy: tongue deviates towards affected side