cranial nerves

CN l

olfactory

CN ll

optic

CN lll

oculomotor

CN lV

trochlear

CN V

trigeminal

CN Vl

abducens

CN Vll

facial

CN Vlll

vestibulocochlear

CN lX

glossopharyngeal

CN X

vagus

CN Xl

spinal accessory

CN Xll

hypoglossal

CN l olfactory - type

sensory

CN l olfactory - function

smell

CN l olfactory - pathway

olfactory receptors in nasal epithelium to olfactory cortex in temporal lobe

CN l olfactory - clinical testing

use aromatic substances to test each nostril separately

CN l olfactory - disorders

anosmia: loss of smell due to trauma, infection, neurodegeneration

CN ll optic - type

sensory

CN ll optic - function

transmit visual info from retina to brain

CN ll optic - pathway

retina to visual cortex in occipital lobe

CN ll optic - clinical testing

assess visual acuity vs Snellen chart, test visual fields, test pupillary reflexes

CN ll optic - disorders

blindness, visual field defects, optic neuritis

CN lll oculomotor - type

motor

CN lll oculomotor - function

controls 4/6 extraocular muscles, pupil constriction via parasympathetic innervation, lens accommodation via ciliary muscles

CN lll oculomotor - pathway

midbrain to superior orbital fissure

CN lll oculomotor - clinical testing

assess eye movements/pupillary size/light reflex

CN lll oculomotor - disorders

ptosis: dropping eyelid, diplopia: double vision, fixed dilated pupil bc of loss of parasympathetic function, trouble with horizontal plane

CN lV trochlear - type

motor

CN lV trochlear - function

controls superior oblique muscles

CN lV trochlear - pathway

midbrain to sinus to orbit

CN lV trochlear - clinical testing

assess downward eye movement while eye is adducted

CN lV trochlear - disorders

vertical diplopia, trouble with vertical plane

CN V trigeminal - type

mixed

CN V trigeminal - function

sensory: provide sensation to the face

motor: innervates muscles of mastication such as masseter and temporalis

CN V trigeminal - pathway

sensory: face, scalp, eyes, mouth, tongue to somatosensory cortex

motor: pons to mandible

CN V trigeminal - clinical testing

assess facial sensation, corneal reflex, jaw movements

CN V trigeminal - disorders

trigeminal neuralgia: severe facial pain, loss of sensation, difficulty chewing

CN Vl abducens - type

motor

CN Vl abducens - function

controls lateral rectus muscle which abducts eye and moves it laterally and out

CN Vl abducens - pathway

pons to lateral rectus muscle

CN Vl abducens - clinical testing

assess lateral eye movement

CN Vl abducens - disorders

diplopia, inability to move the eye laterally, strabismus: eyes not working together

CN Vll facial - function

sensory: taste from anterior 2/3 of tongue

motor: facial expression, salivation, tear formation

CN Vll facial - pathway

sensory: tongue to brainstem

motor: pons to muscles of facial expression, salivary glands, tear ducts

CN Vll facial - clinical testing

test facial movements (smile, frown, raise eyebrows), test taste, test tearing

CN Vll facial - disorders

Bell’s palsy: temporary paralysis of facial muscles, loss of taste, dry eyes or mouth

CN Vlll vestibulocochlear - type

mixed

CN Vlll vestibulocochlear - function

hearing balance, spatial orientation

CN Vlll vestibulocochlear - pathway

sensory: inner ear to brainstem to auditory cortex and balance centers

motor: brainstem to inner ear

CN Vlll vestibulocochlear - clinical testing

audiogram, Romberg test for balance

CN Vlll vestibulocochlear - disorders

tinnitus, vertigo, sensorineural hearing loss

CN lX glossopharyngeal - type

mixed

CN lX glossopharyngeal - function

sensory: taste in posterior 1/3 of tongue, carotid body (helps regulate blood oxygen and pressure)

motor: stylopharyngeus muscle for swallowing

CN lX glossopharyngeal - pathway

sensory: tongue and pharynx to brainstem

motor: medulla to stylopharyngeus muscle which elevates throat during swallowing

CN lX glossopharyngeal - clinical testing

test gag reflex and swallowing

CN lX glossopharyngeal - disorders

loss of gag reflex, dysphagia, impaired taste

CN X vagus - type

mixed

CN X vagus - function

sensory: thoracic and abdominal viscera (internal organs)

motor: pharyngeal and laryngeal muscles

CN X vagus - pathway

sensory: thoracic and abdominal organs to brainstem

motor: medulla to muscles of pharynx and larynx

CN X vagus - clinical testing

assess speech, swallowing, uvula position

CN X vagus - disorders

hoarseness, dysphagia, autonomic dysfunction

CN Xl spinal accessory - type

motor

CN Xl spinal accessory - function

innervates sternocleidomastoid (head rotation) and trapezius (shrugging) muscles

CN Xl spinal accessory - pathway

CN Xl spinal accessory - clinical testing

CN Xl spinal accessory - disorders

CN Xll hypoglossal - type

CN Xll hypoglossal - function

CN Xll hypoglossal - pathway

CN Xll hypoglossal - clinical testing

CN Xll hypoglossal - disorders

why is CN lV trochlear special?

only CN that exits dorsally from the brainstem, longest intracranial course among CNs

CN Vll facial - type

mixed