the eyeball e-learning

8/2/2019 The Eyeball E-learning

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The Eyeball


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The Orbit

Pyramidal-shaped cavity in the skull with its base opening in front

& its apex behind, and contains lacrimal apparatus & eyeball.

4 walls:

Roof ?

Floor ?

Lat. Wall ?

Med. Wall ?


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Muscles of The Orbit

7 musclesLevator palpebrae

Superioris

4 recti muscles

Sup. & Inf. obliques


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Testing for actions of extrinsic eyeballMuscles (H-test)


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The Eyeball

Embedded within orbital fat

except??

Consists of 3 coats1. Fibrous coat:

sclera & cornea

2. Vascular pigmented coat:

choroid, ciliary body & iris

3. Nervous coat:

retina


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Fibrous Coat of Eyeball

Made up of 2 parts

Cornea (L, horn):

Ant., transparent

Fxn.?

Sclera (G, hard):

Post., white (D.C.T.)

Fxn.s? 2

Pierced by:Optic n., ciliary n., & ciliary a.

Lamina Cribrosa?


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Vascular Coat of Eyeball

Composed of:

Choroid (G, skin)pigmented coatcontain melanocytes dark brown in color

(what is the melanin Fxn. In eye?)continues ant. With ?

Ciliary body:ciliary processes (2 fxns.?)ciliary muscle

Iris (L, rainbow):thin contractile pigmenteddiaphragm with centralopening (?)


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Iris:

Pigmented musculardiaphragm between ?

Divides ant. Aspect ofeyeball into ?

Amount of ?? In irisDetermines the eye color

*Contains 2 muscles ?


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Nervous Coat of Eyeball (Retina)

Consists of 2 layers:

Outer pigmented layer

In contact with ?

Inner nervous layer

Contains vision receptors

* Vision receptors = post. 3/4

*Ant. 1/4 = pigment cells

Nonreceptive


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Structures on The Retina

Ora serrata: (serrated edge)

Wavy margin that represents the border between the receptive &nonreceptive parts of the retina

Macula Lutea:Oval yellowish area at the center of post. part of retina that

represents the area of most distinct vision

Fovea Centralis:

The central depression in macula lutea

Optic Disc:

The area where optic n. leaves the retina.

No receptorsblind spotLocated ?


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Contents of The Eyeball

Aqueous Humor (ant.)

Lens (Mid.)

Vitreous Body (post.)


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Aqueous Humor

Clear fluid that fills the space ant. to the lens(ant. & post. chambers)

Secreted by?

Flows through ?

Drained into?

Fxn.:

1. Supports eye wall by exerting internal pressure

2. Nourishes cornea & lens


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Vitreous Body

A transparent gel that fills the space post. to the lens.

Fxn.:

1. Contributes to magnifying power

of the eye

2. Supports post. surface of the lens

3. Holds neural part of retina againstits pigmented part


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Glaucoma

Abnormally high intraocular pressure due to accumulation of

aqueous humor in the ant. Part of the eye

- Most common cause of blindness in US

- Affecting people over 40 years of age

Mechanism:

Fluid compresses lens & vitreous body

Put pressure on the retina Destruction of vision neurons

the eyeball e-learning

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