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OCULAR PHYSIOLOGY > Optic Nerve > Flashcards

Optic Nerve Flashcards

1
Q

Name the 4 parts of the optic nerve head

A

1- surface nerve fiber layer
2-prelimar region
3-lamina cribrosa region
4-retrolaminar

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2
Q

The inner most portion

  • -predominantly nerve fiver
  • -axonal bundle acquire more interaxonal glial tissue as this structure is followed posteriorly
--all of these describe which part of the optic nerve head? 
1- surface nerve fiber layer
2-prelimar region
3-lamina cribrosa region
4-retrolaminar
A

1- surface nerve fiber layer

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3
Q
  • -Fenestrated sheets of scleral connective tissue
  • -Astrocytes separate the sheets and line the holes
  • -Bundle of axons leave through these holes
--all of these describe which part of the optic nerve head? 
1- surface nerve fiber layer
2-prelimar region
3-lamina cribrosa region
4-retrolaminar
A

3-lamina cribrosa region

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4
Q
  • -Also called anterior portion of lamina cribrosa
  • -Predominant structure: nerve axons and astrocytes with significant increase in astroglial tissue
--all of these describe which part of the optic nerve head? 
1- surface nerve fiber layer
2-prelimar region
3-lamina cribrosa region
4-retrolaminar
A

2-prelimar region

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5
Q
  • -Decrease in astrocytes
  • -Myelin is acquired
  • -Axonal bundles surrounded by connective tissue
  • -Posterior limit is not clear but about 3 to 4 mm
--all of these describe which part of the optic nerve head? 
1- surface nerve fiber layer
2-prelimar region
3-lamina cribrosa region
4-retrolaminar
A

4-retrolaminar

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6
Q

The arterial supply of the optic nerve is from the

(posterior/anterior) ciliary artery

A

posterior

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7
Q 
Which part of the optic nerve is not supplied by the posterior ciliary arter? 
1- surface nerve fiber layer
2-prelimar region
3-lamina cribrosa region
4-retrolaminar
A

1- surface nerve fiber layer- supplied by retinal circulation

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8
Q

How many blood vessels supply the optic nerve?

A

6

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9
Q
  • Main supply Arteriolar branches of (____)
  • Anasthamose with the vessels of prelaminar region
  • -all of these supply the surface of the (___)
  • pick one–
  • CRA central retinal artery
  • RPC radial peripapillary capillaries
  • PV pial vessels
  • SPCA short posterior ciliary arteries
  • PCV peripapillary choroidal vessels
  • ZH circle of Zinn-Haller
A

-CRA central retinal artery

Nerve fiber layer

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10
Q
  • -blood vessel supply to the retrolaminar region
  • -Medial and lateral perioptic nerve (___)
  • -Form an elliptical arterial circle around the optic nerve (also called circle of ___)
A

-SPCA short posterior ciliary arteries

ZH- zinn haller

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11
Q
  • blood vessel supply to prelamina and laminar regions
  • primary supply is (__)
  • also supply peripapillary choroid
A

-SPCA short posterior ciliary arteries

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12
Q

What is derived from both retinal and ciliary circulation?

A

capiillaries

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13
Q

Capillaries in the optic nerve resemble capilarries in the (retina/iris/ciliary body)

A

retina

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14
Q

Capillaries in the optic nerve (do/do not) leak fluroescein and may represent ____-blood barrier

A

do not

nerve

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15
Q

Capillaries in the optic nerve (decrease/increase) in number posterior to lamina

A

decrease

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16
Q

Venous drainage for the optic nerve is entirely through the _(central/peripheral) (choroid/retinal) ___ vein

A

central retinal

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17
Q

____ support provides continuous layer between nerve fiber and blood vessels of optic nerve head

A

astroglial

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18
Q

Thin astrocytes accompany the axon on (ZH/NFL/SPCA)

A

NFL

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19
Q

Thick astrocytes are (indirect/direct) axons from prelaminar to laminar region

A

direct

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20
Q

Glaucoma pathogenesis takes place at level of ________ _____ (two words)

A

lamina cribrosa

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21
Q

The lamina cribrosa is the porous region of the (choriod/sclera/retina)

A

sclera

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22
Q

the lamina cribrosa consist of (nonfenestrated/fenestrated) sheets of connective tissue and occacional elastic fibers

A

fenestrated

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23
Q

_____ is found in surrounding the myelin sheaths in the lamina cribrosa

A

hyaluronate

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24
Q

Hyaluronate (increase/decreases) with age and further (increase/decreases) with increase IOP

A

decreases

decreases

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25
Q

T/F in glaucoma the pores of the lamina cribrosa is round in eyes with physiologic cupping.

A

F. In glaucoma the pores of the lamina cribrosa are compressed . Healthy eye they are round in eyes with physiologic cupping

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26
Q

Lamina cribrosa pores are (smaller/larger) superiorly and inferiorly when compared to nasal and temporal

A

larger

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27
Q

Arcuate fibers occupy (inferior/lateral/medial/superior) —pick two—-(lateral/temporal) regions

A

superior and inferior

temporal

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28
Q

Axons from periopheral retinal take more (superior/inferior/peripheral) position

A

peripheral

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29
Q

(Acurate/papillomacular) fibers spread approx 1/3rd of the distal optic nerve primarily inferior temporal.

A

papillomacular

30
Q

T/F retinal nerve fiber layer also intermingles iwth extramauclar fibers (may explain retention of central vision)

31
Q

There are about ____ axons in the optic nerve

a) 1 trillion
b) 1 billion
c) 1 million

32
Q

There are a (large/small) variation of axons in the optic nerve

33
Q

Count of axons in the optic nerve (decrease/increase) with (increase/decrease) in area.

A

increase

increase

34
Q

Axon fiber diameter __to __ µm

a) 0.85-2.10
b) 0.65-2.10
c) 0.85-1.10
d) 0.65 - 1.10

A

0.65 to 1.10

35
Q

T/F Axons in the optic nerve, of all sizes are mixed throughout although mean diameter appear to be more common nasal segment.

36
Q

The size of the optic nerve reaches ___% before age 1

a) 90
b) 85
c) 95
d) 100

37
Q

There is a greater susceptibility of damage , and potential for reversible cupping if a child doesn’t develop the connective tissue of the __ __ completely

A

lamina cribrosa

38
Q

There is a progressive loss of axons in the optic nerve of ___ to ___ a year

a)5500-12000
b4000-10000
c)5000-10000
d)4000 to 12000

A

4000 to 12000

39
Q

T/F It has been proven that there is a selective loss of fibers with age

A

F. It has not been proven but is is a theory of Quigley and group

40
Q

T/F because they eye is not fully developed at birth it can take damage and still “bounce back” and recover depending on the type of damage

41
Q

If there is a accelerated loss of axons in the optic nerve this is from a disease called ___

42
Q

T/F all cells die at an equal rate in the optic nerve

43
Q

Retinal ganglion cells depend upon certain neuronal growth factors called ________

A

neurotrophins

44
Q

T/F Axonal compression at lamina cribrosa block retrograde axoplasmic flow

45
Q

T/F Nitric oxide is beneficial at certain concentration as a vasodilator

46
Q

Nitric oxide at a (higher/lower) concentration can cause neurotoxicity

47
Q

Nitric oxide (activates/inhibits) mitochondrial function and (does nothing to/disrupts) DNA

A

inhibits, disrupts

48
Q

T/F axoplasmic flow is a continuous pulsing , undulating movement of the cytoplsm between the cell body of a neuron , where protein synthesis occurs

49
Q

Physical alterations, misalignment of fenestrae, backbowing of lamina cribrosa may lead to obstruction.

Support to this theory damage with elevated IOP occurs despite intact blood vessels.

    • this describes which theory –
      1. mechanical theory
      2. vascular theory
A

mechanical theory

50
Q

Ischemia at least plays a role in the obstruction of axoplasmic flow in response to elevated IOP.

    • this describes which theory –
      1. mechanical theory
      2. vascular theory
A

vascular theory

51
Q

Perfusion pressure is the difference between ___ and ___ pressure

A

arterial , venous

52
Q

Mean ocular perfusion pressure = mean __-___

53
Q

T/F perfusion pressure states that blood vessel resistance also determines blood flow

54
Q

______ mechanism is present in retinal vessels to maintain blood flow regardless of perfusion pressure

A

autoregulatory

55
Q

The autoregulatory mechanism fails in what type of disease?

56
Q

What are the two types of autoregulator mechanisms?

A

metabolic and myogeneic

57
Q

(metabolic/myogenic) has a unclear mechanism

58
Q

(metabolic/myogenic) endothelial cells secrete vasodilators and vasoconstrictors

59
Q

Nitric oxide is a (vasolidator/vasoconstrictor)

A

vasodilator

60
Q

Endothelin 1 is a (vasodilator/vasoconstrictor)

A

vasocontrictor

61
Q

Raynaud’s phenonmenon has a excessive (constriction/dilation) of vessels to cold

A

constriction

62
Q

Delayed filling of superficial vessels of optic nerve in glaucoma shows that there is a favor to the (mechanical/vascular) theory

63
Q

T/F pt with migraines have a higher association with glaucoma

64
Q

Delayed filling of superficial vessels of optic nerve in glaucoma
Association of NTG with migraines
Excessive peripheral constriction of vessels to cold- Raynaud’s phenomenon
Nocturnal blood flow different in glaucoma patients
Greater plasma concentration of endothelin-1
– all of these show a favor for (mechanical/vascular) theory

A

vascular theory

65
Q

T/F it is not clear whether mechanical or vascular factors are primary

66
Q

Obstruction of the axoplasmic flow may be involved in pathogensis of (diabetes/glaucoma)

67
Q

in a healthy optic disc the nuerual rim is broadest in which area? (inferiorly/superiorly/nasal/temporally)

68
Q

T/F in a healthy optic disc the disc is (smaller/larger) in area then teh neural rim

69
Q

Tilted disc syndrome has a (vertically/horizontally) oval disc

A

horizontally

70
Q

T/F The myopic optic dissc has a sloped and tilted contour, and difficult to accuratly assess the extent of the disc rim thinning –(making it harder to diagnose glaucoma)

OCULAR PHYSIOLOGY (13 decks)

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