I: UII CN III

Question 1

What type of nerve is CN III?

Answer 1

Motor; somatic and parasympathetic

Question 2

Which two muscles are not supplied by CN III?

Answer 2

Superior oblique and lateral rectus

Question 3

What does CN III innervate?

Answer 3

Extra ocular eye muscles except for two

Question 4

What are oculomotor nuclei?

Answer 4

Somatic nuclei of origin

Question 5

Where are the somatic nuclei of origin located?

Answer 5

In periaqueductal gray, anterior to cerebral aqueduct at level of superior colliculi

Question 6

What part of the cerebral cortex sends axons to the oculomotor nuclei?

Answer 6

BMA #8

Question 7

What other areas send fibers to the oculomotor nuclei?

Answer 7

Superior colliculi and medial longitudinal fasciculus

Question 8

How do CN III axons travel?

Answer 8

Anterior through red nucleus, exit CNS via interpeduncular fossa (into cistern)

Question 9

As the axon of CN III exits the CNS, what is it covered in?

Answer 9

Epineurium (continuos with dura mater)

Schwann cells cover every fiber

Question 10

How does CN III nerves enter the skull?

Answer 10

Penetrates the dura, travels along cavernous sinus, exit skull via superior orbital fissure, enters eye socket

Question 11

In the eye socket, what does CN III split into?

Answer 11

Superior and inferior rami

Question 12

What muscles are supplied by the superior ramus of CN III?

Answer 12

Superior rectus

Levator palpebra superiorus

Question 13

What muscles are supplied by the inferior ramus of CN III?

Answer 13

Medial rectus by medial branch
Inferior rectus by central branch
Inferior oblique by lateral branch

Question 14

What does the accessory oculomotor nuclei contain?

Answer 14

Preganglionic parasympathetic neurons

Question 15

How do axons from the accessory oculomotor nucleus travel?

Answer 15

Follow the oculomotor nerve and synapse in ciliary ganglion

Question 16

Where is the ciliary ganglion located?

Answer 16

Posterior to the eyeball, ~1 cm anterior to the superior orbital fissure

Question 17

What is another name for the postganglionic parasympathetic axons of CN III?

Answer 17

Short ciliary nerves

Question 18

What course do short ciliary nerves travel?

Answer 18

Follow course of ciliary arteries, pierce the sclera and travel along the internal surface of the sclera to supply things

Question 19

What two structures do the short ciliary nerves supply?

Answer 19

Ciliaris muscle: contraction makes lens more convex
Pupillary constrictor (sphincter pupillae): constricts pupil

Question 20

Does the ciliary body also carry other types of nerves?

Answer 20

Yes: sympathetic and somatic sensory fibers

Question 21

Where are the sympathetic and somatic sensory fibers of the ciliary ganglion picked up from?

Answer 21

Ophthalmic nerve (V1), just pass through, no synapse

Question 22

What is CN III?

Answer 22

Oculomotor nerve