Week 9: Eyes, Skull, Cranial Nerves

Question 1

The zygomatic process, the supraorbital foramen and the supraorbital margin are all part of which bone?

Answer 1

The frontal bone

Question 2

Forms the majority of the roof of the orbit, as well as the floor of the cranial fossa.

Answer 2

Frontal bone

Question 3

The zygomatic bone contributes to which border of the orbital margin?

Answer 3

Inferolateral border and both the lateral walls and the floor of the orbit.

Question 4

The maxilla forms which border of the orbital margin?

Answer 4

Inferomedial border of the orbital margin and contributes to the orbital floor.

Question 5

The sphenoid bone forms which wall of the orbit?

Answer 5

The posterior wall, leaving “gaps” or fissures for structures to pass through.

Question 6

Where is the optic canal located?

Answer 6

The optic canal is seen in the medial aspect of the lesser wing of Sphenoid.

Question 7

What structures traverse through the optic canal?

Answer 7

The optic n. and the ophthalmic a.

Question 8

What 2 branches of the trigeminal n. traverse through the inferior orbital fissure?

Answer 8

The infraorbital and the zygomatic.

Question 9

What structures traverse the superior orbital fissure?

Answer 9

Cranial nerves III, IV, V and VI. They are:

• oculomotor n.
• trochlear n.
• trigeminal n.
• abducens n.

And superior and inferior ophthalmic v.

Question 10

Bones that form the medial wall of the orbit AND make up the border of the superior optical fissure and optic canal.

Answer 10

Ethmoid and palatine bones.

• The lacrimal bone also forms the medial wall of the orbit.

Question 11

On a blow to the face, which bone is more likely to become damaged?

Answer 11

The orbital surface of the maxilla is the most likely bone to be damaged because it is very thin, followed by the ethmoid bone.

Question 12

The lacrimal bone forms the medial wall of the orbit and has a fossa called…

Answer 12

Lacrimal fossa, where the lacrimal sac sits.

Question 13

Cranial Nerves

Answer 13

I Olfactory n. 
II Optic n.
III Oculomotor n. 
IV Trochlear n.
V Trigeminal n.
VI Abducens n.
VII Facial n.
VIII Vestibulocochlear n.
IX Glossopharyngeal n.
X Vagus n.
XI Accessory n.
XII Hypoglossal n.

Question 14

What are the three basic layers of the eyeball?

Answer 14

Outer coat, middle coat and inner coat.

The outer coat consists of the cornea and sclera. Function: strength.

The middle coat consists of the uvea (choroid, iris, ciliary body). Function: nutrition.

The inner coat consists of the retina and its main fuction is vision.

Question 15

What are the three chambers of the eyeball?

Answer 15

Anterior chamber: Aqueous humor
Posterior chamber: Aqueous humor
Vitreous chamber: Vitreous humor

Question 16

The __________ is the spot in the retina where there are no interneurons but heaps of photoreceptors, which allows for high detail vision.

Answer 16

Fovea

Question 17

All muscles of the eye are innervated by the oculomotor n. except for

Answer 17

→ Superior oblique: trochlear n.

→ Lateral rectus: abducens n.

Question 18

Describe the vascular supply to the orbit and retina

Answer 18

Comes from the opthalmic a. which is a branch of the internal carotid a.

4 branches of ophthalmic a.

Central retinal a.
Long posterior ciliary a.
Short posterior ciliary a.
Anterior ciliary a.