Cranial Nerves

CN I

olfactory

CN I function

ability to detect odor

lesion of CN I causes __

anosmia (loss of smell)

CN II

optic

CN II function

visual acuity

lesion of CN II

loss of visual acuity, blindness

CN III

oculomotor

CN III function

eye movement, pupillary light reflex

• innervates superior rectus, medial rectus, inferior rectus, and inferior oblique

lesion to CN III

diplopia (double vision), mydriasis (dilated or blown pupil) & photophobia, cycloplegia (blurred near vision due to flattened lens)

CN IV

trochlear

CN IV function

eye movements

• innervates superior oblique only

lesion of CN IV

diplopia (double vision)

CN V

trigeminal

CN V function

somatosensation and bite strength

lesion to CN V

numbness or pain, tingling, difficulty chewing

• trigeminal neuralgia (chronic disorder featuring severe facial pain)

CN VI

abducens

CN VI function

eye movements

• innervates lateral rectus only

lesion to CN VI

diplopia (double vision)

CN VII

facial

CN VII function

facial expressions

lesion to CN VII

weakness/paralysis, xerophthalmia (dry eye), loss of taste

• Bell’s palsy (drooping facial expression)

CN VIII

vestibulocochlear

CN VIII function

hearing (cochlea), balance and equilibrium (vestibular apparatus)

lesion to CN VIII

loss of hearing and balance; tinnitus (ringing) and vertigo, nausea

CN IX

glossopharyngeal

CN IX function

swallowing and gag reflex

lesion to CN IX

numbness at pharynx, loss of sensation and tate fro posterior tongue

CN X

vagus

CN X function

swallowing

lesion to CN X

dysphagia (difficulty swallowing), dysphonia (hoarseness), tachycardia (increased HR)

CN XI

accessory

CN XI function

ability to shrug and turn head

lesion to CN XI

atrophy of trapezius, weakness in elevation of scapula and rotation of neck

CN XII

hypoglossal

CN XII function

movement of tongue

lesion to CN XII

dysarthria (slurred speech)