Eyeball

Question 1

Name all the layers of the cornea and describe them breifly

Answer 1

1) Epithelium:

• stratified squamous non-keratinized
• no connective tissue papillae

2) Bowman’s membrane:

• Thick acidophilic basment membrane
• Collagen fibres, no cells

3) Stroma (substansia propria)

• several layers highly regular collagen fibres, in transparent ground substance
• contains fibroblasts

4) Descemet’s membrane

• Thin acidophilic basment membrane
• Collagen fibres

5) Endothelium

• Simple squamous epithelium
• Serves nutrition to the cornea from the anterior chamber

Question 2

Describe the blood supply and innervation of the cornea

Answer 2

Avascular tissue

Rich sensory innervation by the long ciliary nerve (CN.V/1)

Question 3

Describe the conjunctiva

Answer 3

• The epithelium of the cornea is continuous with that of the conjunctiva.
• Several connective tissue papilla
• Lamina propria (loose c.t.)

Question 4

1. What is the composition (tissue) of the sclera?
2. Which structure is found in the corneo-scleral junction?
3. What is the function of this structure?

Answer 4

1. Made up of dense connective tissue (connective tissue and fibrocytes)
2. Canal of Schlemm (sinus venousus sclerae)
3. Lined by endothelium - draining the aqueous humor from the anterior chamber

Question 5

Choroid

A) Where is it located?

B) What are its layers?

Answer 5

A) Highly vascular layer on the inner surface of the sclear

B) Layers:

• 1. Suprachoroidal lamina* (highly pigmemnted c.t. cells with nerves and vessels)
• 2. Vascular lamina* (arterioles and venules)
• 3. Choriocapillary layer* (network of fenestrated capillaries - nutrition of outer retina)
• 4. Buch’s membrane* (lamina basalis - separating it from the retina, elastic and collagen fibres and basal lamina)

Question 6

What are the layers of the blood-retina barrier?

Answer 6

5 layers (in a “choroid to retinal” direction):

• Fenestrated capillaries of the choroid
• Collagen fibres
• Elastic fibres
• Collagen fibres
• Retinal pigment epithelium (with thight junctions)

Question 7

Ciliary body

1) Describe its composition
2) a. What is the indicated structure?
b. What is the function of this structure?
3) Its inner surface is covered by …
4) a. Which structure is not mentioned so far?
b. What are the two components of this structure?

Answer 7

1) Thickening of the vascular coat composed of loose c.t.

2) a. Ciliary process

b. production of aqueous humor into the posterior chamber

3) Part of the retina - two layers: unpigmented inner and pigmented outer

4) a. Ciliary muscle

b. 1) Meridional - Bürke portion

2) Readial and circular - Müller portion

Question 8

What are the components of the blood-aqueous humor barrier?

Answer 8

• Basal lamina of the capillaries
• Epithelial cells of the ciliary body (connected with zona occludens) and their basal lamina

Question 9

Iris

A) 1. Covers (partly) which other structure of the eye?

2. What is the uncovered part called?

B) List and describe (breifly) the layers:

C) What is the innervation of the dilator - & sphincter pupillae m.?

D) What is the embryonical orgin of dilator pupillae m.?

Answer 9

A) 1. Lens

2. Pupil

B) 1. Endothelium - of the anterior chamber, simple squameous epithelium, fibroblasts and pigmented cells

2. Stroma - loose c.t. with fibroblasts and pigment c.t. cells., sphincter pupillae m., anastomosing arterioles (greater and lesser iridic circles)
3. Dilator pupillae m.
4. Pigment layer - double layer of hevaly pigmented melanocytes

C) 1. Dilator pupillae m. - parasympathetic (ciliary ggl.)

2. Sphincter pupillae m. - sympathetic

D) Neuroectoderm

Question 10

Retina

A) What is found behind and in front of the ora serrata?

B) List the layers and describe brifely:

Answer 10

A) Behind: photosensitive region

In front: blind region

B) Layers:

1. Pigment epithelium - simple cuboidal epithelial cells with melanin pigment granules
2. Rods and cones - photosensitive receptor cells
3. Outer limiting membrane - (very thin - not seen) barrier line, formed by peripherial processes of the Müller glial cells
4. Outer granular (nuclear) layer - nuclei of rods and cones
5. Outer plexiform layer - first synaptic layer
6. Inner granular (nuclear) layer - nuclei of the bipolar cells (and horizontal amacrine cells, and Müllerian glial cells)
7. Inner plexiform layer - second synaptic layer
8. Ganglion cell layer - large nuclei of the ganglion cells, usually one row only (forms the optic nerve)
9. Optic nerve fibres - found together with vessels (branches of central retinal arteries and veins)
10. Inner limiting membrane - (thin, sharp line) innermost part of vitreous body, made by the inner processes of the Müller glial cells.

Question 11

1. Where is the fovea centralis located?
2. What is special for its function?
3. Which receptor cells are found here?

Answer 11

1. In the macula lutea (yellow spot)
2. Area of greatest photosensitivity
3. Only cones

Question 12

1. Another name of the optic disc/optic papilla?
2. Which receptorcells are found here?
3. Which other structures are found here?

Answer 12

1. Blind spot
2. No receptor cells
3. Optic nerve fibres leaves the retina, penetrating through the sclera

Question 13

What covers the optic nerve outside the eye ball?

Answer 13

All three meninges

Question 14

Lens

1. What is the outermost layer of the lens?
2. What is found under this layer in tha anterior surface?
3. What cell type makes up the strongly eosinophilic biconvex structure of the lens (the lens itself without covering)?

Answer 14

1. Lens capsule - homogenous
2. Simple cuboidal lens epithelium
3. Lens fibres - (hadrly seen) not connective tissue, derived from surface ectoderm