Lecture 32 DA

Question 1

Where is the supraorbital margin?

Answer 1

The frontal bone directly under the eyebrow, forming a ridge.

Question 2

What is the dint above the supraorbital margin called, and what passes here?

Answer 2

Supraorbital notch. Neurovascular vessels to the forehead pass here.

Question 3

Where is the infraorbital margin? What forms it.

Answer 3

Directly inferior to the eyeball. Formed by zygomatic bone laterally and maxilla medially.

Question 4

What is the superior roof of the orbit?

Answer 4

Orbital plate of the frontal bone.

Question 5

What forms the posterior wall of the orbit?

Answer 5

Lesser wing of sphenoid laterally, and ethmoid bone medially.

Question 6

What can be found on the medial wall of the orbit?

Answer 6

Ethmoid bone and lacrimal bone.

Question 7

What is the structure of the ethmoid bone like?

Answer 7

Very thin, called papyrus region for this reason.

Question 8

What forms the floor of the orbit?

Answer 8

Maxilla medially, zygoma laterally, and palatine superior to the two.

Question 9

What can be found on the lateral wall of the orbit?

Answer 9

Zygomatic bone.

Question 10

Why do some bones in the orbit break so easily?

Answer 10

They break to protect the eye so pressure doesn’t damage it.

Question 11

What passes through the optic canal?

Answer 11

Optic nerve with the ophthalmic artery.

Question 12

What nerves pass through the superior orbital fissure?

Answer 12

Ophthalmic division of the trigeminal nerve and extraocular muscle nerves.

Question 13

What forms the superior orbital fissure?

Answer 13

Gap between lesser and greater wing of sphenoid.

Question 14

Where is the inferior orbital fissure?

Answer 14

Inferior to the superior orbital fissure.

Question 15

What are the three layers of the eye?

Answer 15

Outer coat
Cornea/sclera

Middle layer
Uvea

Inner coat
Retina

Question 16

What is the purpose of the sclera?

Answer 16

Strength, is very tough and durable. Maintains shape, attachment for muscles and resists forces.

Question 17

What is the purpose of the uvea?

Answer 17

Mostly supplies nutrition to the eye.

Question 18

What is the purpose of the retina?

Answer 18

Vision.

Question 19

How much of the eye is the sclera?

Answer 19

Posterior 5/6ths, and is white.

Question 20

What is the cornea and sclera made of?

Answer 20

Collagen.

Question 21

Is the cornea vascular?

Answer 21

No.

Question 22

How much of the eye is the cornea?

Answer 22

Anterior 1/6th.

Question 23

What are the layers of the cornea?

Answer 23

Epithelial layer
Stroma - collagen
Endothelium

Question 24

Whats so special about the endothelium?

Answer 24

Its unique, and are born with a certain number. Maintains water balance and cornea thickness. Doesn’t regenerate.

Question 25

Why is the cornea transparent if it and the sclera both have collagen?

Answer 25

Collagen in the cornea is parallel, ordered and stacked at a different angle over one another with all the same size. The sclera has a whorly arrangement with different sizes, unordered and random.

Question 26

What is the anterior chamber angle, and what does it do?

Answer 26

Juntcion between cornea and iris. Aqueous humour drains out of the eye here.

Question 27

What is the trabecular meshwork? Where does it drain to?

Answer 27

A sieve-like structure that drains the eye, and drains into Schlemm's canal inferiorly.

Question 28

Where is the aqueous humour formed?

Answer 28

In the ciliary body of the uvea.

Question 29

What tether's the lens?

Answer 29

Ciliary processes (ciliary epithelium) of the uvea, via zonules (ligaments).

Question 30

What do ciliary muscles allow the eye to do?

Answer 30

Accomodation.

Question 31

What other fluid is aqueous humour like?

Answer 31

Cerebrospinal fluid.

Question 32

Does aqueous humour have protein?

Answer 32

Very little.

Question 33

What does the aqueous humour do?

Answer 33

Provides nutrition and intraocular pressure.

Question 34

What is accomodation?

Answer 34

Ability to focus on something close up.

Question 35

What is involved in accomodation?

Answer 35

Ciliary muscles and their ligaments called zonules attaching to the lens.

Question 36

Is ciliary muscle contraction voluntary?

Answer 36

No, it is smooth muscle.

Question 37

What happens to the lens when ciliary muscles contract?

Answer 37

The zonules aren't under tension, and the lens becomes fat and wider, focusing closer.

Question 38

What happens to the lens when ciliary muscles relax?

Answer 38

Zonules are under tension, and the lens becomes thin and narrow.

Question 39

What is the iris?

Answer 39

Coloured aperture of the eye.

Question 40

What two muscles forms the iris, which is anterior and posterior?

Answer 40

Sphincter pupillae - Anterior | Dilator pupillae - Posterior

Question 41

What is the function and innervation of the two iris muscles?

Answer 41

Sphincter pupillae - constricts the eye, parasympathetic innervation. Dilator pupillae - dilates the eye, sympathetic innervation.