8 Cranial Nerves Of Eye And Orbit

Question 1

List the cranial nerves associated with the eye, orbit, and associated structures (7).

Answer 1

(CNs 2-7, minus V3)

CN II: optic nerve
CN III: oculomotor 
CN IV: trochlear 
CN V: trigeminal (ophthalmic and maxillary divisions) 
CN VI: abducens nerve
CN VII: facial nerve

Question 2

Describe the location and path of each cranial nerve, starting from the cavernous sinus area and ending at its terminal branches:

Trigeminal Nerve, V1.1
(ophth div: nasociliary nerve)

Answer 2

The nasociliary runs along medial aspect of the orbit. After splitting off branches to the 2 long ciliary nerves and the sensory root to the ciliary ganglion, it continues traveling medially and gives rise to 2 more medial branches: posterior ethmoidal nerve and, soon-after, the anterior ethmoidal nerve. It continues along to become the infratrochlear nerve as it exits the orbit below the trochlea to penetrate the orbital septum and receives sensory fibers to the surrounding area of the medial canthal: caruncle, canaliculi, lacrimal sac, medial aspect of the eyelids, and skin at the side of the nose.

Question 3

What are the branches of V1?

Answer 3

V1 leaves Trigeminal ganglion and goes through the cavernous sinus. It soon splits into three branches:

1. Lacrimal Nerve
2. Frontal Nerve
3. Nasociliary Nerve

Question 4

Describe the location and path of each cranial nerve, starting from the cavernous sinus area and ending at its terminal branches:

Trigeminal Nerve, V1.2
(ophth div: Frontal Nerve)

Answer 4

• Enters the orbit through the superior orbital fissure above the common tendinous ring.
• The Frontal Nerve splits into the Supraorbital nerve and Supratrochlear nerve midway through the orbit.
• Supratrochlear receives fibers of skin and muscles of the forehead and upper eyelid.
• Supraorbital nerve (accompanied by s/o artery) exits through the supraorbital notch and receives from (more laterally) the skin and muscles of the forehead and upper eyelid.

Question 5

Describe the location and path of each cranial nerve, starting from the cavernous sinus area and ending at its terminal branches:

Trigeminal Nerve, V1.3
(Ophth Div: Lacrimal Nerve)

Answer 5

• Branches off in lateral fashion to the Frontal Nerve (V-1.2).
• Enters orbit via Suprior Orbital Fissure, above the muscle cone.
• Splits into a branch containing the autonomic innervation of the lacrimal glad, the zygomatic nerve.
• Terminates at sensory fibers from the lacrimal gland and lateral aspect of the upper eyelid and temple area.

Question 6

discuss the components of each cranial nerve discussed: motor, sensory, autonomic

list and describe the fxn of each cranial nerve discussed

Answer 6

…

Question 7

The ophthalmic nerve (V-1) exits the ____ wall of the cavernous sinus (with respect to a posterior-to-anterior direction).

Answer 7

lateral

Question 8

Describe the location and path of each cranial nerve, starting from the cavernous sinus area and ending at its terminal branches:

Trigeminal Nerve, V-2.1
(Max div: Infraorbital Nerve)

Answer 8

(-V2 splits into two branches: infraorbital nerve and zygomatic nerve.)

• Infraorbital Nerve, the more medial of the two, enters orbit through the inferior orbital fissure.
• While in the Maxillary bone, gives off branches to upper teeth and maxillary sinus.
• Exits Maxillary bone through the infraorbital foramen.
• Receives sensory fibers from cheek, upper lip, lower eyelid.

Question 9

Describe the location and path of each cranial nerve, starting from the cavernous sinus area and ending at its terminal branches:

Trigeminal Nerve, V-2.2
(Max div: Zygomatic Nerve)

Answer 9

…

• Zygomatic Nerve exits Zygomatic bone as:
  1. zygomaticofacial nerve, goes to receive sensory fibers from the lateral aspect of the cheek and lower eyelid
  2. zygomaticotemporal nerve, goes to receive sensory fibers from the lateral aspect of the forehead (also has communicating branch to the lacrimal nerve of V-1)

Question 10

The lacrimal nerve leaves the lacrimal gland and runs _____ along the upper border of the _________ muscle.

Answer 10

posteriorly

lateral rectus

Question 11

The lacrimal nerve exits the orbit through the __________ and ______ the muscle cone.

Answer 11

superior orbital fissure

above

Question 12

With respect to a posterior to inferior direction, the infraorbital nerve exits the maxillary bone through the __________.

Answer 12

infraorbital foramen

Question 13

The _______ nerve passes near the pterygopalatine fossa and receives some autonomic fibers from the pterygopalatine ganglion.

Answer 13

maxillary

Question 14

The cranial nerves that supply the motor functions of the orbit and adnexa are:

Answer 14

CN III (oculomotor)
CN IV (trochlear)
CN VI (abducens)
CN VII (facial)

these motor nerves are the e-fferent pathway

Question 15

The ________ nerve pierces the roof of the cavernous sinus and runs within the two dural layers of the lateral wall, above the trochlear nerve.

Answer 15

oculomotor

Question 16

While in the cavernous sinus, the oculomotor nerve sends small sensory branches to the _______ nerve and receives sympathetic fibers from the _________.

Answer 16

ophthalmic

plexus around the internal carotid artery

Question 17

CN III enters the orbit through the ________.

CN III divides into _____ and _____ divisions, but both divisions are still located within the _______ foramen.

Answer 17

superior orbital fissure

superior, inferior
oculomotor

Question 18

The superior branch of the ______ runs medially above the optic nerve and enters the superior rectus on its _____ surface.
Additional fibers pierce either the muscle or pass around its border to innervate the _______.

Answer 18

oculomotor nerve (CN III)

inferior

levator palpebrae superioris

Question 19

The inferior branch of the _______ runs below the _____ and divides into 3 branches:

1. One enters the medial rectus on its ______.
2. One enters the inferior rectus on its ______.
3. One gives off _______ fibers that form the ________ extending to the ciliary ganglion.

Answer 19

oculomotor nerve (CN III)

1. lateral side
2. upper surface
3. parasympathetic, parasympathetic root

Question 20

The _____ nerve is a motor-only nerve that innervates the superior oblique muscle.

This nerve enters the wall of the cavernous sinus and lies between the ______ and the ________(of ___).

While in the cavernous sinus, it sends sensory fibers to ______.

Answer 20

trochlear (think SO4)

oculomotor nerve (CN III)
ophthalmic division of the trigeminal nerve (CN V)

the ophthalmic nerve

Question 21

The trochlear nerve, CN IV, enters the orbit through the __________ fissure at a point (above/below) the common tendinous ring and (inside/outside) the muscle cone.
CN IV runs alongside the ______ to the medial side of the orbit above the _______ (2 muscles) and enter the upper surface of the ________ muscle, where it innervates.

Answer 21

superior orbital
above
outside

frontal nerve (of V-1)
levator muscle and superior rectus muscle
superior oblique

Question 22

1. Within the cavernous sinus, the abducens, CN VI, is tucked right up against this non-nerved structure and it’s small sympathetic branches (from it’s plexus) leave to travel alongside the abducens.
2. The abducens carries these autonomic fibers and sensory fibers to the ___________ division of the trigeminal nerve.

Answer 22

1. (the lateral wall of) the internal carotid

2. ophthalmic division

Question 23

CN VI enters the orbit through the _______ and (inside/outside) of the common tendinous ring.

The abducens innervates the _________ muscle on the ______ surface.

Answer 23

superior orbital fissure
inside

lateral rectus (LR6)
medial

Question 24

1. The motor fibers of the facial emerge through the ________ and then pass below the __________ canal, travel over the ________ ramus, and divide into several branches.
2. What are the upper two branches?
3. What do they supply?

Answer 24

1. stylomastoid foramen
   external auditory canal
   mandibular ramus
2. temporal branch, zygomatic branch
3. the frontalis, procerus, corrugator, and orbicularis muscles.

Question 25

There are 2 roots of the facial nerve: a large, motor root and a small, sensory and parasympathetic root.

1. What do each carry?
2. Which one includes the lacrimal gland?

Answer 25

1. The large motor root innervates the facial muscles
   The smaller root contains sensory and parasympathetic fibers.
   -The sensory fibers carry taste sensations from the tongue.
   -The parasympathetic nerves supply secretomotor fibers to various glands of the face.
2. The parasympathetic nerves supply the secretomotor fibers to the lacrimal gland.