Cranial Nerve III Oculomotor Nerve

Question 1

anisocoria bigger in light then dark indicates__?

Answer 1

issue with constricting

Question 2

describe Oculomotor nerve (CNIII)?

Answer 2

largest of the cranial nerves that innervate the extraocular muscles

Question 3

Damage to the superior division of the oculomotor nerve

Answer 3

can result in ptosis (dropping of eyelid) and difficulty moving eye medially or upwards

Question 4

somatic motor (superior division of oculomotor nerve) innervates what muscles?

Answer 4

SR, MR, IR, IO and the LPS muscle

Question 5

what cranial nerves are the EOMS innervated by?

Answer 5

lateral rectus = CN VI (6)
Superior oblique = CN IV (4)
all other muscles CN III

Question 6

the somatic motor innervates the following EOM muscles

Answer 6

SR, MR , IR, IO & LPS

Question 7

the oculomotor nucleus project ___?

Answer 7

ipsilaterally except those to SR and LPS

Question 8

the oculomotor nucleus project SR and LPS_____?

Answer 8

SR= contralateral
LPS = bilateral

Question 9

once the oculomotor nerve exits the nucleus all fibers____?

Answer 9

all fibers supply the ipsilateral eye & lesions of the nerve after it leaves the nucleus will cause unilateral deficiets

Question 10

if there is any crossing over to the contralateral side, it’s happening in the____ once its left the brain___?

Answer 10

brainstem itself once its left the brain all of these fibers are on route to the same eye (ipsilateral)

Question 11

CN III is located ____?

Answer 11

the dorsal aspect and lateral wall of cavernous sinus between the dural layers

Question 12

the fibers that innervate the pupil are located____ why is this important in pts with pupil involving cranial nerve palsy?

Answer 12

superficially (surface) of the nerve; because of this arrangement, the fibers that control the pupil are prone to compression when a patient presents with a pupil involving cranial nerve palsy these patients are likely to have compression issues like tumors, aneurysm. This is an issue and needs to be referred ASAP

Question 13

how does cranial nerve III exit?

Answer 13

branches into superior and inferior division in anterior part of cav. sinus or immediately upon exiting sinus

Question 14

Any pupil-involving, partial or non- isolated CN III palsy requires ______

Answer 14

urgent neurological assessment!!

Question 15

Cranial nerve palsies are considered non- isolated if they are ________ including ___?

Answer 15

associated with other neurological signs or specific systemic risk factors including:
-Signs of orbital disease
- Multiple CN palsies / other neurological signs
-Systemic /Infectious or inflammatory factors
- Severe headache

Question 16

Pupil sparing lesions more likely to be associated with_____?

Answer 16

ischemic/microvascular cause