Special Senses 2

Question 1

The Eye - Layers

Corneoscleral coat

Answer 1

Outermost later. Cornea is transparent anterior extension of sclera

Question 2

The Eye - Layers

Uveal tract

Answer 2

Middle layer. Consists of iris and ciliary body anteriorly and vascularized choroid coat posteriorly

Question 3

The Eye - Layers

Retina

Answer 3

Inner layer consisting of layers of nerve cells, their processes, support cells and, on the outside, a layer of pigmented epithelium

Question 4

The Eye - Layers

Biconvex Lens

Answer 4

Present along with layers. Elastic, allowing it to change shape to permit accomodaton for near vision

Question 5

The Eye - Layers

Anterior and Posterior chambers

Answer 5

Sit in front of the lens and are filled with aqueous humor. Posterior to the lens is the bigger vitreal cavity full of vitrious humor which is avascular and gelatinous

Question 6

The Cornea

Outer layer

Answer 6

Thin stratified squamous epithelium on thin layer of collagen called Bowman’s membrane.

Question 7

The Cornea

Stroma

Answer 7

Makes up most of the thickness of the cornea. Made of many laters of precisely oriented, hydrated collagen

Question 8

The Cornea

Duscemet’s membrane

Answer 8

Inside of the layers. Endothelium sitting on a layer of collagen.

Question 9

Anterior of the Eye

Sclera

Answer 9

Tough coat of collagen and elastic fibres defining the globe. Tendons of the extraocular muscles attach to sclera

Question 10

Anterior of the Eye

Ciliary body

Answer 10

Contains smooth muscle that, during nearvision, releases tension on the zonular fibres allowing the lens to round-up due to its natural elasticity

Question 11

Anterior of the Eye

Excess fluid from anterior chamber

Answer 11

Drained via the canal of schlemm into blood vessels. Glaucoma results when this drainage is not adequate

Question 12

Anterior of the Eye

Iris

Answer 12

Mostly loose connective tissue with a layer of pigmented epithelium on its posterior surface. Contains melanocytes.

Question 13

Anterior of the Eye

Iris muscle

Answer 13

Contains smooth muscle that changes it’s diameter

Question 14

Anterior of the Eye

Dilator pupillae

Answer 14

Muscles are radially oriented and, under sympathetic stimulation, they open the pupil

Question 15

Anterior of the Eye

Sphincter pupillae

Answer 15

Fibres located near the tip and are circumferentially oriented. Constrict pupil under parasympathetic stimulation

Question 16

Lens

What is it?

Answer 16

Transparent spherical structure made up of lens fibres.

Question 17

Lens

Lens Fibres

Answer 17

Lens fibres are long cells that lose their nuclei as they mature, and most organelles are packed with proteins called crystallins.

Question 18

Lens

Anterior covering

Answer 18

Anteriorly, the lens is covered by an outer connective tissue capsule and a layer of simply cuboidal epithelium.

Question 19

Retina

What is it?

Answer 19

Complex, thin layer of nervous tissue lining the inner eye. Within the retina is a characteristic layered structure

Question 20

Retina

Rods and cones

Answer 20

Distribution of these is not uniform. Rods predominate away from the fovea but are absent at the fovea.

Question 21

Fovea of Retina

Foveola

Answer 21

Fovea is at the centre of the optical axis on the retina. At the centre of the fovea is the foveola. The retina thins and is avascular at the foveola, and there are only cones found here covered by the outer plexiform layer

Question 22

Retina

Optic disc

Answer 22

Lacks photoreceptors. Otherwise known as the “blind spot”.