topic 3 sclera

Question 1

what are the 3 functions of the sclera?

Answer 1

1. protection
2. support
3. anchorage for structures

Question 2

what is the composition of the sclera?

Answer 2

75% collagen

25% proteins

Question 3

how many opening does sclera have?

Answer 3

several openings to allow blood vessels and nerves to enter (not continuous)

Question 4

where is the sclera the weakest?

Answer 4

at the site of attachment of the recti muscles

Question 5

what is the blood supply of the sclera?

Answer 5

anteriorly supplied by ciliary arteries

posteriorly supplied by circle of haller-zinn (formed by posterior ciliary artery)

Question 6

what is the nerve supply of the sclera?

Answer 6

trigeminal nerve (5) long (post) and short (ant) ciliary verves

Question 7

what are the 3 layers of the sclera?

Answer 7

episclera. scleral stroma, lamina fusca

Question 8

what are 3 characteristics of episclera?

Answer 8

1. anterior most layer
2. highly vascularized
3. tenon’s capsule is anterior to this layer

Question 9

what are 3 characteristics of scleral stroma?

Answer 9

1. made of collagen fibres of variable thickness and random arrangement
2. this increases strength of stroma and makes it opaque
3. avascular

Question 10

what are 4 characteristics of lamina fusca?

Answer 10

1. inner most layer
2. formed by collagen fibres
3. pigmented bc of melanocytes
4. separated from choroid by perichoroidal space