S 1.2 Eyeball - pt.1 - A Flashcards

1
Q

The wall of the eyeball has three concentric coats which enclose three compartments, namely:

A

anterior, posterior and vitreous chambers

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2
Q

What are the three coats found in the eyeball?

A

A. Outer fibrous coat / Sclerocorneal layer
B. Middle vascular coat / Uveal tract
C. Inner photosensitive coat / Retina

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3
Q

This coat consists of the opaque posterior four-fifth, the sclera and the anterior transparent one-fifth, the cornea. The sclera and cornea become continuous with each other at the limbus or the sclerocorneal junction.

A

Outer Fibrous Coat / Sclerocorneal Layer

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4
Q

Outer Fibrous Coat / Sclerocorneal Layer

A
  • Sclera
  • Cornea
  • Sclerocorneal Junction / Limbus
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5
Q
  • It is a dense regular connective tissue resembling that of ligaments and tendons, provides rigid structural support for the eyeball
  • It is composed mostly of dense collagen fibers and few elastic fibers
  • It is separated externally from Tenon’s capsule (fascial sheath of eyeball) by episcleral layer of loose connective tissue (Tenon’s space) and internally from the choroid by lamina fusca (suprachoroidal lamina) of dark pigmented fibroelastic tissue.
  • Posteriorly it is pierced by axons of ganglionic cells of retina at lamina cribrosa to form optic
    nerve.
A

Sclera

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6
Q

Sclera:
- a _______ ________ connective tissue resembling that of ligaments and tendons, provides rigid structural support for the eyeball

A

dense regular

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7
Q

Sclera:
It is composed mostly of dense _________ fibers and few ______ fibers.

A

collagen; elastic

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8
Q

Sclera:
It separated externally from ________ _______ (fascial sheath of eyeball) by episcleral layer of loose connective tissue (Tenon’s space) and internally from the
_________ by lamina fusca (suprachoroidal lamina) of dark pigmented fibroelastic tissue.

A

Tenon’s capsule; choroid

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9
Q

Sclera:
Posteriorly it is pierced by axons of ganglionic cells of _______ at _________ _______ to form optic nerve

A

retina; lamina cribrosa

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10
Q
  • It is a dense connective tissue with a layer of epithelium on both sides—is about 0.5 mm thick, 11.5 mm in diameter, transparent, and resistant to deformation.
  • It occupies one-fifth of the ocular surface, with its radius of curvature less than that of the rest of the eyeball.
  • Its anterior surface is nonkeratinized stratified squamous epithelium, about 50 µm thick and consisting of 3-6 layers of cells, except near the periphery, where it is 8-10 layers.
  • Basal cells are polygonal, but the most superficial cells, which retain nuclei, are flattened.
  • The epithelium continuously replicates, and it regenerates in response to wear and tear.
A

Cornea

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11
Q

Cornea:
It is a dense connective tissue with a layer of epithelium on both sides—is about ____ mm thick, ____ mm in diameter, transparent, and resistant to deformation

A

0.5; 11.5

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12
Q

Cornea:
Its anterior surface is ___________ ___________ __________ epithelium, about 50 µm thick and consisting of _____ layers of cells, except near the periphery, where it is _____ layers.

A

nonkeratinized stratified squamous; 3-6; 8-10

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13
Q

Cornea:
Basal cells are __________, but the most superficial cells, which retain nuclei, are _________.

A

polygonal; flattened

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14
Q

Cornea:
The epithelium continuously replicates, and it regenerates in response to wear and tear. Its rich sensory nerve supply (from the ___________ branch of cranial nerve V) is sensitive to _______ and _______.

A

ophthalmic; touch; pain

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15
Q

Cornea:
A layer of tears lubricates the ________surface

A

anterior

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16
Q

Cornea:
Deep to the epithelium is ___________________

A

Bowman’s membrane

17
Q

Cornea:
—a prominent basement membrane, 8-15 µm thick—that binds epithelium to underlying connective tissue

A

Bowman’s membrane

18
Q

Cornea: Bowman’s membrane
a prominent basement membrane, _____ µm thick—that binds _________ to underlying connective tissue

A

8-15; epithelium

19
Q

Cornea:
The thick central region, the ___________, contains 60-70 layers of type I collagen fibers, which are uniform in diameter and embedded in a proteoglycan-rich extracellular matrix

A

substantia propria

20
Q

This is misnamed corneal endothelium—lines the posterior surface

A

Simple cuboidal epithelium

21
Q

Cornea:
Its basement membrane (10-12 µm thick) is __________________.

A

Descemet’s membrane

22
Q

Cornea:
Most of it relies on ____________ of oxygen and nutrients from aqueous humor.

A

diffusion

23
Q

The boundary between cornea and sclera (white of the eye) is an abrupt transitional zone, the _______, where mucous membranes covering the sclera (_______ conjunctiva) and underside of the
eyelid (________ conjunctiva) join the anterior corneal epithelium.

A

limbus; bulbar; palpebral

24
Q

-It is marked by a shallow depression externally and it is the place where the transparent cornea becomes continuous with the opaque sclera.
- It contains an important circular canal lined by endothelium called canal of Schlemm or scleral venous sinus concerned with drainage of aqueous humour as this canal is connected externally to the anterior ciliary veins and internally to the anterior chamber through spaces of Fontana at iridocorneal angle.

A

Sclerocorneal Junction / Limbus

25
Q

Sclerocorneal Junction / Limbus:
It is marked by a shallow depression externally and it is the place where the transparent _______ becomes continuous with the opaque ________.

A

cornea; sclera

26
Q

Sclerocorneal Junction / Limbus:
It contains an important circular canal lined by endothelium called canal of ________ or __________ ________ _________ concerned with drainage of aqueous humour as this canal is connected externally to the anterior ciliary veins and internally to the anterior chamber through spaces of ________ at iridocorneal angle.

A

Schlemm; scleral venous sinus; Fontana

27
Q

Sclerocorneal Junction / Limbus:
______________ ________ is dialysate of blood. It is a clear watery fluid (similar to CSF in composition) produced by the ciliary epithelium, covering the ciliary processes into the posterior chamber.

A

Aqueous humour

28
Q

Sclerocorneal Junction / Limbus:
__________ ___________ serves as a medium for exchange of metabolites to and from the avascular lens and cornea. It is also responsible for the intraocular pressure (normal pressure is 20 mmHg).

A

Aqueous humour