Oculomotor (CN3), trochlear (CN4) and abducent (CN6) nerves

Question 1

2 functions of CN III (what type of nucleus for each function)

Answer 1

1. Somatic motor - Oculomotor nucleus
2. Visceral motor (parasympathetic) - accessory motor nucleus (Edinger-Westphal nucleus)

Question 2

What is Ciliary ganglion?

Answer 2

A parasympathetic ganglion of the oculomotor nerve [III]

Question 3

Ciliary ganglion It is associated with ____ (nerve?)

Answer 3

the nasociliary branch of the ophthalmic nerve [V1]

Question 4

Location of ciliary ganglion?

Answer 4

Located in the posterior part of the orbit, between the optic nerve & the lateral rectus muscle

Question 5

Ciliary ganglion

The postganglionic parasympathetic fibers leave the ganglion through (1)____ which enter the posterior aspect of the eyeball.

Answer 5

short ciliary nerves

Question 6

Ciliary ganglion

The postganglionic parasympathetic fibers leave the ganglion through short ciliary nerves, which enter the posterior aspect of the eyeball.

In the eyeball the parasympathetic fibers innervate ___

Answer 6

• *Sphincter pupillae muscle** —> Pupillary constriction
• *Ciliary muscle** —> Accommodation of the lens of the eye for near vision

Question 7

course of trochlear nerve

Answer 7

• Brain exit: Below inferior colliculi on both sides of the frenulum of superior medullary velum (dorsal aspect of brain)
• Dural exit: Cavernous sinus (lateral wall), within the anterior Petro-clinoidal fold
• Skull exit: Superior Orbital fissure

Question 8

Course of abducent nerve (CN 6)

Answer 8

• Brain exit: At the ponto-medullary junction (medullopontine sulcus)
• Dural exit:
  
  • Cavernous sinus (freely)
  • Ascends in the clivus in the Dorello’s canal; enters the cavernous sinus far below the post. petroclinoidal fold
• Skull exit: Superior Orbital fissure