CN VI

Question 1

CN VI is called what?

Answer 1

abducens nerve

Question 2

IT lies where?

Answer 2

posterior cranial fossa

Question 3

it emerges from where?

Answer 3

pontomedullary junction most medially

Question 4

What two arteries does it pass between?

Answer 4

the anterior inferior cerebellar artery and internal auditory artery

Question 5

Where does it pass forward?

Answer 5

lyes on the clivus and then crosses over the apex of the petrous part of the temporal bone

Question 6

How does it pass the middle cranial fossa? Where does it enter? lateral to what?

Answer 6

it passes forward into the middle cranial fossa, and enters the cavernous sinus lateral to the internal carotid artery

Question 7

How does it enter the orbit?

Answer 7

Through the superior orbital fissure?

Question 8

CN VI innervates which muscle?

Answer 8

the lateral rectus muscle- abducts the eye = turns eye out laterally

Question 9

(LR6SO4)3 means what?

Answer 9

lateral rectus muscle is innervated by 6
superior oblique muscle is innervated by 4
the other four extraocular muscles are innervated by 3

Question 10

compression of the abducen nerve. Anything that forces the brainstem downward or forward would strecth the CN VI fibers as they emerge from the brainstem and pass along the clivus.
What four things could happen?

Answer 10

1. meingiomas growing on the clivus
2. cerebral edema
3. pontine or cerebellar tumors push forward and compress CN VI against the clivus
4. head trauma