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Eye anatomy > Ocular Structures > Flashcards

Ocular Structures Flashcards

1
Q

Cornea

A

transparent, connective tissue membrane

set into the sclera

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2
Q

Average diameter of Cornea

A

Vertical 11.5mm

Horizontal 12.0mm

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3
Q

Average thickness of the Cornea at the limbus

A

0.7-0.9mm

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4
Q

How many layers make up the Cornea?

A 
5
Epithelium 
Bowman'membrane 
Stroma
Descemet's membrane
Endothelium
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5
Q

Where does the Cornea receive its nourishment from?

A

Tear film that covers and the aqueous humor that flows beneath it.
The cornea has no blood vessels.

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6
Q

What is the junction between the sclera and cornea called?

A

Limbus

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7
Q

What is the main function of the cornea?

A

To focus light rays reflected to the eye

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8
Q

Pars Plana

A

external periphery of the retina

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9
Q

Zonule Fibers

A

resemble fibers of a spider’s web spread out between the ciliary body and the crystalline lens and fix the crystalline lens in a central position - behind the iris and the pupil.

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10
Q

Pupil

A

circular opening in the center of the iris.

the eye can adapt rapidly to changes in light by opening and closing the pupil.

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11
Q

Sclera

A

white outer layer of the eye
stabilizes the eye
starts at the front edge of the limbus and covers the eye to the posterior optic nerves

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12
Q

What does the Sclera comprise of?

A

dense, white fibrous tissue

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13
Q

What is the main function of the Sclera?

A

to protect the contents of eyeball.

it also helps to prevent the scattering of light rays

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14
Q

What are the six extra-ocular muscles that have their insertions on the sclera?

A 
Lateral Rectus (LR)
Medial Rectus (MR)
Superior Rectus (SR)
Inferior Rectus (IR)
Superior Oblique (SO)
Inferior Oblique (IO)
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15
Q

Conjunctiva

A

thin, translucent mucous membrane that lines the inner surface of the top and bottom eyelids and the outer surface of the eyeball except for the cornea.

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16
Q

What helps the eyelids to slide easily against the outer surface of the eyelid?

A

the slippery nature of the conjunctival tissue and the folds in the fornix

17
Q

Limbus

A

the transition from the transparent cornea to the white opaque sclera

18
Q

Iris

A

comparable to the aperture of a camera
coloured part of the eye
situated behind the cornea and in front of the lens

19
Q

Eye colour is determined by?

A

the number of brown pigment cells on its surface - blue eyes have very few pigment cells

20
Q

Two Iris muscles

A

the actions of the muscles are either to contract or dilate the pupil, controlling the amount of light entering the inner part of the eye.

21
Q

sphincter muscle

A

the circular muscle in the iris that constricts the pupil.

parasympathetic nerve activity that normally innervates this muscle.

22
Q

dilator muscle

A

the radial muscle in the iris that dilates the pupil

sympathetic nerve activity that normally innervates this muscle.

23
Q

What divides the anterior and posterior chambers of the eye?

A

the iris

24
Q

What do both the anterior and posterior chambers of the eye contain?

A

aqueous humour

25
Q

Retina

A

sticks like wallpaper to the posterior eyeball.

it is the light sensitive part of the eye and is comparable to the film of a camera.

26
Q

what is at the center of the retina?

A

macula

27
Q

what does retinal thickness vary between?

A

0.1 and 0.5mm

28
Q

Optic nerve head

A

optic nerve runs from the optic nerve head to the visual centre in the brain.
it consists of approx 1 million nerve fibres

29
Q

Macula

A

area at the center of the retina- important for focuse vision and reading

30
Q

Diameter of the macula?

A

approx 5.5mm

31
Q

Diameter of the optic nerve?

A

3 and 4mm

32
Q

Crystalline lens

A

directly behind the iris

it bundles the light falling in through the pupil and generates an image on the retina.

33
Q

Ciliary body

A

continuous with the root of the iris and is mainly muscle fibres.
production of aqueous humor and for accomadation

34
Q

accomadation

A

when the ciliary muscle contracts, causing a change in the curvature of the crystalline lens. This is how the eye adjusts itself to focus on near or distant objects.

35
Q

where do the suspensory ligaments have their insertions?

A

the ciliary body

36
Q

What does contraction/ relaxation of the suspensory ligaments do?

A

alter the shape of the lens

37
Q

what is produced by the ciliary processes?

A

aqueous humour

38
Q

aqueous humour

A

provides nourishment for intraocluar structures and also helps to maintain the intraocular pressure at an average of 15mmHg in the adult eye

39
Q

lower fornix

A

fornix is an anatomical structure that is arched or vault like.
when either lower lids are gently pulled down it exposes a loose pocket of conjunctival tissue - the fornix.
the lower fornix can be used as an excellent trap for drops and ointments as well as material such as debris and foreign matter.

Eye anatomy (1 decks)

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