Cranial nerves

Question 1

What is cranial nerve 1

Answer 1

olfactory - smell sensory information
originates at the olfactory mucosa of nasal cavity and terminates at the olfactory bulb at the base of frontal lobe

only sensory input that bypasses the thalamus and doesnt use to relay sensory info to cortical areas

exits through cribriform plate of ethmoid

Question 2

what is cranial nerve 2

Answer 2

optic nerve - sight sensory info
left field of view from left eye travels to left side of optic tract to occipital lobe, while right field of view from left eye crosses at the optic chiasm, going to the right side of the occipital lobe

originates at the retina of the eye and terminates at the lateral geniculate of the thalamus

exits thru optic foramen

Question 3

what is cranial nerve 3

Answer 3

oculomotor - eyetracking and the eyelid, also responsible for proprioception

damage to this nerve leads to drooping eyelid, dilated pupil, loss of accomodation, double vision, and inability to move eye

functional test involves testing ability to track moving objects

exits through the superior orbital fissure

Question 4

what is cranial nerve 4

Answer 4

trochlear nerve - motor eye movements ( down and inwards)

functional test involves asking the patient to look down and inwards

exits through the superior orbital fissure

Question 5

what is cranial nerve 5 (all branches)

Answer 5

ophthalmic branch - sensory for upper face, exits through superior orbital fissure, functional test is checking for blinking in response to eyeball touching

maxillary branch - sensory for middle face, exits thru foramen rotundum, functional test is using a pinprick to test facial sensation

mandibular branch - motor for the muscles of chewing (mastication) and sensory for the lower face, exits thru foramen ovale/mental foramen, functional test includes asking pt to open mouth, and test sensation with pinprick

Question 6

what is cranial nerve 6

Answer 6

abducens nerve - motor eye movement (moving eye laterally)

exits through superior orbital fissure

functional test is lateral eye movement

Question 7

what is cranial nerve 7

Answer 7

facial nerve - mixed (facial expressions and taste sensory)

exits through the stylomastoid foramen

damage causes facial drooping and drooling on one side, with distorted taste

functional test is to check for hemifacial weakness and evaluating taste buds

Question 8

what is CN8

Answer 8

vestibulocochlear - sensory hearing and equilibrium (balance)

exits through internal acoustic meatus

damage causes impaired hearing and vertigo

functional test involves hearing tests and balance tests

Question 9

What is CN9

Answer 9

glossopharyngeal nerve - mixed sensory (taste/baroreceptors) and motor (elevation of larynx/pharynx)

functional test - gag reflex and check for problems with swallowing

Question 10

what is CN10

Answer 10

Vagus nerve - mixed nerve - most autonomic functions, motor in speech/swallowing, sensory for pharynx and larynx

exits jugular foramen

functional tests - observe speech and swallowing ability, and symmetry of palate

Question 11

what is CN11

Answer 11

accessory nerve - motor for neck and traps

exits through jugular foramen

functional tests involve testing for impairment with sternocleidomastoid and traps

Question 12

what is CN 12

Answer 12

hypoglossal nerve - motor for tongue movement

exits through hypoglossal canal

functional tests - get pt to stick out tongue, any deviation to one side indicates CN12 defect