Cranial Nerves

Question 1

Which cranial nerves are related to the eye?

Answer 1

2- optic
3- oculomotor
4- trochlear
5- trigeminal
6- abdomens
7- facial

Question 2

Blow-out fracture of orbit -> numbness along face/teeth that runs along flow of the orbit - think of?

Answer 2

CN5 Trigeminal (maxillary and/or mandibular division) being affected

Question 3

Divisions of Trigeminal nerve V?

Answer 3

V1- ophthalmic
V2- maxillary
V3- mandibula

Question 4

Innervation of:

• Muller’s m
• Levator palpabrae superioris
• Orbicularis m

Answer 4

Muller - sympathetic ANS (can’t voluntarily control)
Levator - oculomotor n
Orbicularis- facial n

Question 5

Difference between levator and Muller’s and orbicularis m?

Answer 5

Levator- lid elevation out of the line of vision
Muller- lifts the eyelid (always contracted unless asleep)
Orbicularis- forceful closure + normal blinking

Question 6

Pt: difficulty eating, slurred speech, HA, R side of face’s muscle tone diff to L, droopy upper and lower lids on mainly RE.

Think of?
Why?

Answer 6

CN7- Facial nerve affected

Controls facial m and orbicularis occuli m

Question 7

How to check Facial nerve is working?

Answer 7

Face muscles (frontalis, orbicularis - oculi and oris, buccinator)

Motor:
Test frontalis m
- Raise your eyebrows and crease forehead

Test orbicularis oculi
- Close your eyelids, squeezing them close

Test orbicularis oris

• Smile for me- moves the corner of the mouth upwards
• Assess symmetry- should be same left and right

Question 8

Cont Pt:
Everything tested normal but the orbicularis oculi. Can’t close RE.
Goes further to test CN5 trigeminal - corneal sensitivity
Touch L cornea –> reflex blink both eyes
Touch R cornea –> no blink
Sensation felt both corneas.

Identify and explain the diagnosis.

Answer 8

DD: CN7 Facial nerve abnormal –> can’t innervate the orbicularis m –> dysfunctional blink reflex and voluntary closure of RE