Special Senses (Eye) Flashcards

1
Q

What is the eye?

A

organ of vision very important to human survival

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2
Q

What is contained within the eye?

A

more than ½ of sensory receptors of human body

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3
Q

What is 40% of the cerebral cortex for?

A

devoted to processing of visual information

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4
Q

What is the eyeball supported and protected by?

A

accessory structures including eyelids, extraocular muscles, and lacrimal apparatus

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5
Q

Eyeball

What is the shape?

A

symmetric, spherical structure

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6
Q

Eyeball

What is the eyeball surrounded by?

A

layer of loose connective tissue that allows its relatively free movement within orbital cavity

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7
Q

Eyeball

What are the 3 layers or tunics of the eyeball?

A

fibrous layer (tunic)
vascular layer
nervous layer

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8
Q

Eyeball - Fibrous Layer (Tunic)

What is the fibrous layer (tunic)?

A

outermost layer

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9
Q

Eyeball - Fibrous Layer (Tunic)

What is the sclera?

A

posterior ⅚ of fibrous layer made up of white-ish dense connective tissue

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10
Q

Eyeball - Fibrous Layer (Tunic)

What does the sclera do?

A
  • protects inner parts of eyeball
  • serves as attachment site for extraocular muscles
  • maintains shape of eyeball
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11
Q

Eyeball - Fibrous Layer (Tunic)

What penetrates the posterior aspect of the sclera?

A
  • optic nerve

- blood vessels

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12
Q

Eyeball - Fibrous Layer (Tunic)

What is the cornea?

A

anterior ⅙ of layer that is transparent, lacks blood vessels, and is covered by conjunctiva

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13
Q

Eyeball - Fibrous Layer (Tunic)

What does the cornea do?

A

contribute in focusing light onto retina

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14
Q

Eyeball - Vascular Layer

What is the vascular layer?

A

middle layer that consists of 3 parts

  • choroid
  • ciliary body
  • iris
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15
Q

Eyeball - Vascular Layer

What is the choroid?

A

forms posterior ⅚ of layer and lines inner surface of sclera

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16
Q

Eyeball - Vascular Layer

What does the choroid do?

A
  • highly vascularized and nourishes retina

- carries melanin pigments that absorbs light rays and prevents reflection of light within eyeball

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17
Q

Eyeball - Vascular Layer

What is the ciliary body?

A

anterior continuation of choroid

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18
Q

Eyeball - Vascular Layer

What does the ciliary body do?

A

secretes aqueous humour and modifies convexity of lens

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19
Q

Eyeball - Vascular Layer

What is the core of the ciliary body formed by?

A

ciliary muscle (circular smooth muscles fibers)

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20
Q

Eyeball - Vascular Layer

What are suspensory ligaments?

A

delicate fibres stretched between inner surface of ciliary body, and circumference of lens

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21
Q

Eyeball - Vascular Layer

What does contraction of ciliary muscle do?

A

alters convexity of lens to adapt for near vision

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22
Q

Eyeball - Vascular Layer

What does relaxation of ciliary muscle do?

A

alters convexity of lens to adapt for far vision

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23
Q

Eyeball - Vascular Layer

What is the iris?

A

anterior ⅙ of vascular layer

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24
Q

Eyeball - Vascular Layer

What does the iris form?

A

vertical disc in front of lens, and behind cornea

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25
Q

Eyeball - Vascular Layer

What is the core of the iris formed by?

A

smooth muscle fibers arranged in circular or radial manner

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26
Q

Eyeball - Vascular Layer

What is the pupil?

A

central opening of iris whose diameter is altered by contraction of smooth muscles fibers, which determines amount of light entering eyeball

27
Q

Eyeball - Vascular Layer

What does parasympathetic activation of the iris do?

A

contracts circular muscle fibers that entails constriction of pupil

28
Q

Eyeball - Vascular Layer

What does sympathetic activation of the iris do?

A

contracts radial muscle fibers that leads to dilation on pupil

29
Q

Eyeball - Vascular Layer

What does the iris carry?

A

melanin pigments, and the amount determines eye colour

30
Q

Eyeball - Nervous Layer

How many parts of the nervous layer are there?

A

2

31
Q

Eyeball - Nervous Layer

What is the retina?

A

posterior ¾ of nervous layer that carries photoreceptors that are sensitive to light

32
Q

Eyeball - Nervous Layer

Describe the anterior ¼ of the nervous layer.

A

doesn’t have any photoreceptor, but carries pigments and lines ciliary body and posterior surface of iris

33
Q

Eyeball - Nervous Layer

Where does the optic nerve leave the retina?

A

optic disc (blind spot), which lacks photoreceptors

34
Q

Eyeball - Nervous Layer

What is the macula lutea?

A

situated lateral to optic disc, and is very sensitive to light due to abundance of colour detecting photoreceptors

35
Q

Eyeball - Nervous Layer

What is the fovea centralis?

A

center of macula lutea that contains highest concentration of these colour detecting photoreceptors

36
Q

Lens

What is the lens?

A

transparent, biconvex, elastic body that lacks blood vessels

37
Q

Lens

Where is the lens?

A

posterior to iris

38
Q

Lens

What holds the lens in place?

A

suspensory ligaments that act as tendons of ciliary muscles

39
Q

Interior of Eyeball

What are the 3 chambers?

A

anterior chamber
posterior chamber
vitreous chamber

40
Q

Interior of Eyeball

Where is the anterior chamber?

A

lies between cornea and iris

41
Q

Interior of Eyeball

What is the anterior chamber filled with?

A

aqueous humour (a clear fluid)

42
Q

Interior of Eyeball

What does aqueous humour do?

A
  • cushions lens and cornea

- provides transport system for nutrients and waste materials

43
Q

Interior of Eyeball

Where is the posterior chamber?

A

lies behind iris and in front of lens, and is continuous with anterior chamber through pupil

44
Q

Interior of Eyeball

What is the posterior chamber filled with?

A

aqueous humour, that is secreted by ciliary body

45
Q

Interior of Eyeball

Where does aqueous humour flow in the posterior chamber?

A

fills posterior chamber, flows through pupil, fills anterior chamber, and eventually drains into canal of Schlemm (scleral venous sinus) at junction of sclera and cornea

46
Q

Interior of Eyeball

Where is the vitreous chamber?

A

lies between lens and retina

47
Q

Interior of Eyeball

What is the vitreous chamber filled with?

A

vitreous body (vitreous humour) - clear jelly-like substance

48
Q

Interior of Eyeball

What does vitreous body (vitreous humour) do?

A
  • helps maintain shape of eyeball
  • cushions lens
  • holds retina against choroid
49
Q

Interior of Eyeball

When does vitreous body (vitreous humour) form?

A

during embryonic life

50
Q

Interior of Eyeball

Compare vitreous body (vitreous humour) vs. aqueous humour.

A

vitreous body (vitreous humour) does not undergo constant turnover, unlike aqueous humour

51
Q

What are the 3 accessory structures of the eye?

A
  • eyelids (palpebrae)
  • lacrimal apparatus
  • extraocular muscles
52
Q

Eyelids (Palpebrae)

What are eyelids?

A

thin skin folds in front of eyeball that protect eye against excessive light and foreign objects

53
Q

Eyelids (Palpebrae)

What is the core of the eyelids formed by?

A

tarsal plate (fibroelastic plate) and skeletal muscles

54
Q

Eyelids (Palpebrae)

What is the inner surface lined by?

A

conjunctiva - mucous membrane that reflects on eyeball to cover cornea

55
Q

Eyelids (Palpebrae)

What is found at the free margin of eyelids? (3)

A

eyelashes
sweat glands
sebaceous glands

56
Q

Lacrimal Apparatus

What is the lacrimal apparatus composed of? (4)

A

group of structures that produce and drain tears

  • lacrimal gland
  • lacrimal canaliculi
  • lacrimal sac
  • nasolacrimal duct
57
Q

Lacrimal Apparatus

Where is the lacrimal gland?

A

occupies superolateral part of orbital cavity

58
Q

Lacrimal Apparatus

What does the lacrimal gland do?

A

release tears on surface of eye – tears are swept across ocular surface by blinking movements of eyelids and are collected at medial corner of eye

59
Q

Lacrimal Apparatus

What are the lacrimal canaliculi?

A

pair of small tubes on medial corner of eye that drain tears into lacrimal sac

60
Q

Lacrimal Apparatus

What is the lacrimal punctum?

A

opening of lacrimal canaliculi

61
Q

Lacrimal Apparatus

What is the lacrimal sac?

A

membranous sac that fills lacrimal groove of lacrimal bone, and receives tears from lacrimal canaliculi

62
Q

Lacrimal Apparatus

What is the nasolacrimal duct?

A

distal continuation of lacrimal sac which empties into lateral wall of nasal cavity at inferior nasal meatus

63
Q

Extraocular Muscles

What are extraocular muscles?

A

extrinsic muscles of eye that arise from different parts of orbit, and insert to sclera

skeletal muscles that move eyeball in different directions

64
Q

Extraocular Muscles

What are the intrinsic muscles of the eye?

A

smooth muscles of iris and ciliary body