Lecture 26 - Eye and Orbit Flashcards Preview

Viscera & Visceral Systems > Lecture 26 - Eye and Orbit > Flashcards

Flashcards in Lecture 26 - Eye and Orbit Deck (43):
1

What are the margins of the orbit?

Supraobital margin
- formed by the frontal bone

Infrobital margin
- zygomatic bone (laterally)
- maxilla (medially)

2

Why is the supraorbital notch imporatnt?

allows communication of nerves and BV going to the forehead

3

What bones form the orbit roof, floor, lateral and medial wall?

Roof
-Frontal bone

Floor
-maxilla
zygomatic, palatine

lateral Wall
Zygonmatic, greater wing of sphenoid

Medial wall
- maxilla, lacrimal bone, ethmoid, body of sphenoid

4

Which bones are likely to break in the orbit

thin and weak ones - lacrimal and part of the ethmoid

5

where is the optic canal located

Within the body of the sphenoid - for the optic nerve and its artery

6

Where is the superior orbital fissure?

in the sphenoid

7

Where is the inferior orbital fissure?

between sphenoid and maxilla

8

What are the 3 layers of the eye:

Outer coat:
cornea & sclera - strength

Middle: Uvea - nutrition

Inner: retina

9

describe the sclera

forms 5/6th of the eyeball

maintains the shape of the globe, offering resistance to internal and external forces

provides attachment for muscles

each collagen fibre forms in whirls - added strength than a parallel laydown like a ball of string

10

Describe the cornea

Anterior - 1/6th of eye

Prinicpal refrecting component of the eye

Avascular and transparent = optimum for vision

11

What is the structure of the cornea?

5 layers histologically

Epithelium
Bowman's layer
Stroma (large - collagenous)
Desccment's membrane
Endothelium

12

what percentage of light refraction occurs at the cornea?

60%

13

The stroma is continuous with the ..

.sclera (the collagen is continous)

14

the sclera and cornea(stroma) are..

pretty much the same histologically - yet one is transparent and one isn't

15

What is the structure of collagen in the cornea?

uniform, evenly spaced
run in parallel - because it's so ordered, provides transparency

16

Scleral opacity is affected by...

collagen fibres of different length, distribution - no order, looks white

17

Where is the anterior chamber

The anterior chamber (AC) is the fluid-filled space inside the eye between the iris and the cornea's innermost surface, the endothelium.[1] Aqueous humor is the fluid that fills the anterior chamber. Hyphema and glaucoma are two main pathologies in this area. In hyphema, blood fills the anterior chamber. In glaucoma, blockage of the canal of Schlemm prevents the normal outflow of aqueous humor, resulting in accumulation of fluid, increased intraocular pressure, and eventually blindness.

18

What are the key strucutres in the AC angle?

cornea
trabecular meshwork
Canal of schlemn
ciliary body

19

What are the functions of the ciliary body?

produces the aqueous humour

Tethers lens (ciliary processes)

Accomodation (ciliary muscle)

20

what is the importance of the aqueous humour

maintaining health of lens

creates intraocular resssure

21

ciliary process is made of

two layers of ciliary epithelium

22

How is the aqueous humour drained?

through pupil, and then trabecular meshwork twoards venous drainage

23

What is involved in accomudation?

ciliary muscles
zonules (tiny ligaments)

24

Ciliary muscle runs a ring around your..

iris

25

contraction is for looking at things...

close up - the lensbecomes "buldgy"

26

The iris is part of the..

urea

27

Which muscles control the iris? What innervates each?

sphincter pupillae: constricts pupil - parasymp

Dilator pupillae: dilates pupil - symp n.

28

The choroid consists of ...

3 layers of blood vessels

Most important is the choriocapillaris, which sits just below the retina

supplies nutrients to retina

29

The macular part of the retina allows you to see ____

centrally

30

True of False

The macular is void of blood vessels

true

31

What is the posterior pole?

region around the macular on the retina

32

The area where the retina cmeets the rest of the eyeball?

ora serrata

33

Right in the middle of the macular is a special area called

the fovea

34

The fovea is the part where we focus on.....

what is its make up in terms of rods/cones?

central vision

high density of cones / no rods

35

The optic nerve is formed by the axons of ______ cells as they exit the retina to pass visual information to higher cortical areas

The optic nerve is formed by the axons of ganglion cells as they exit the retina to pass visual information to higher cortical areas

36

True or false

the optic nerve pierces all 3 layers of the eyeball

true

37

1/3 of the collagen that forms the sclera continues across the optic nerve - what is this called?

lamina cribosa - forms a siv through which the processes pass

gives structure

38

The opthalmic artery is a branch of the

carotid a.

39

The central retinal artery travels where?

pierces the optic nerve enters the retina and fans out

40

The long and short posterior ciliary arterybranch from the...

opthalic a

long ones travel further in the eyeball

41

What supplies the anterior sections of the eye orbit?

anterior ciliary artery

42

the retina has a dual blood supply - what suppies what?

Central retinal artery supplies the inner retina

posterior ciliary artery supplies the outer retina (photoreceptors)

43

Anterior ciliary arteries anastomose with the long posterior ciliary arteries via the ...

major perforating artery