Lecture 4 - CN V and VI

Question 1

does CN V (trigeminal) have motor or sensory responsibilities

Answer 1

both

Question 2

how to test for CN V

Answer 2

• observe face for jaw muscle atrophy, fasciculations and jaw deviation
• have patient tightly clench the teeth on tonge depressor

Question 3

how to test for sensory function on CN V

Answer 3

sharp, dull, and light touch sensation on all three divisions (forehead, inferior eye, lower chin)

Question 4

how to test for corneal reflex (sensory function) of CN V

Answer 4

have patient look up and away from you, lightly touch th ecornea o fone eye with cotton wisp

• symmetric blink reflex should occur

Question 5

if only 1 eye blinks during corneal reflex, what is the result

Answer 5

CN VII on the other eye doesn’t work, CN V works

Question 6

sharp stabbing pain lasting seconds in usually one division of CN V

Answer 6

trigeminal neuralgia or tic doloroux

• not often seen bilaterally
• more common in female than male
• > age 50 usually

Question 7

what are the two common causes of trigeminal neuralgia

Answer 7

• abberant superior cerebellar artery
• cerebellar pontine angle tumor

Question 8

motor function is evaluated by having the patient perform a series of facial expressions

Answer 8

CN VII

Question 9

• upper facial muscles are controlled by ____ cortex or cortices
• lower facial muscles are controlled by _____ cortex or cortices

Answer 9

• upper = both cortices
• lower = contra cortex

Question 10

which tumor is most likely to effect CN VII

Answer 10

pontine lesion - 4th ventricle tumor

• can lead to lateral rectus palsy: head turns to side of palsy

Question 11

what are the two peripheral nerve lesions

• ____ neuroma
• ______ palsy

Answer 11

• acoustic neuroma: 8th nerve, in genu of facial canal (7th and auditory of 8th)
• facial (bell’s) palsy: weakness of fascial muscles (ipsi side), also decreased taste of tongue, increased hearing, and decreased tear production

Question 12

acoustic neuroma is most commonly caused by

Answer 12

cerebellar pontine angle tumor

Question 13

neuroma (schwann cell tumor) of the vestibular portion of VIII in the fascial canal

Answer 13

acoustic neuroma

• very slow growing tumor (patients compensate while they lose it)

Question 14

what is the sensory function of CN VII

Answer 14

taste of anterior 2/3 tongue (salty and sweet)

Question 15

what nerve innervates the posterior 1/3 of tongue (bitter and sour)

Answer 15

CN IX