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Block 12 Ellen > L15: The visual system > Flashcards

L15: The visual system Flashcards

1
Q

the path an image takes from the eye is

A
  • optic nerve
  • past the optic chiasm into the
  • optic tract,
  • to the lateral geniculate nucleus
  • to the primary visual cortex in the back of the brain
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2
Q

what is the thalamic relay centre in the brain for images

A

geniculate nuclei

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3
Q

where in the brain does everything from the left visual field of both eyes go

A

right hemisphere

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4
Q

where do the fibres become purely one visual field

A

after the optic chiasm in the optic tract

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5
Q

if there is a lesion in the optic nerve on the right side what happens

A

loss information from the right eye only

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6
Q

homonymous defect =

A

when the information in a single visual field in both eyes is affected

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7
Q

what is damaged in a homonymous defect

A

optic tract

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8
Q

what can you get if only a part of optic radiation is damaged

A

quadrantanopia

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9
Q

what is macular sparing

A

very centre of visual field is the only preserved vision

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10
Q

why does macular sparing happen

A

central eye is highly innervated and has a good blood supply so less likely to be damaged

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11
Q

what happens when the optic chiasm is damaged

A

heterogeneous hemianopia

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12
Q

what is heterogeneous hemianopia

A

loss of vision in opposite hemifields in each eye

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13
Q

2 parts of outermost layer of eye

A
  • cornea

- sclera

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14
Q

sclera=

A

white of eye

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15
Q

cornea=

A

clear bit at the front

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16
Q

3 continous layers of the vascular layer

A
  • iris
  • ciliary body
  • choroid
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17
Q

choroid=

A

network of blood vessels

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18
Q

neural layer of the eye=

A

retina

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19
Q

2 humours of eye

A

aqueous humour

vitreous humour

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20
Q

aqueous humour 2 parts =

A

anterior chamber

posterior chamber

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21
Q

where is the anterior chamber

A

just inside the cornea

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22
Q

where is the posterior chamber

A

between the lens and the iris

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23
Q

2 blood supplies in the eye

A
  • the choroid

- retinal blood vessels

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24
Q

fovea=

A

region of highest resolution vision, highest density of neurons

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25
Q

what is the fovea good at

A

fine detail and high sensitivity

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26
Q

conjugate eye movement=

A

eyes move in the same direction

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27
Q

4 types of conjugate eye movement

A
  • vestibulo-ocular
  • optokinetic -saccade
  • smooth pursuit
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28
Q

1 type of disconjugate eye movement

A

-vergence

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29
Q

saccade=

A

directs eyes towards visual target

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30
Q

name 6 extraocular muscles

A
  • Superior oblique
  • inferior oblique
  • superior rectus
  • medial rectus
  • lateral rectus
  • inferior rectus
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31
Q

2 muscles on top of one another

A
  • levator palpebrae superioris

- superior rectus

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32
Q

which muscle is on a kinda hook

A

superior oblique

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33
Q

which muscles elevate the eye

A
  • superior rectus

- inferior oblique

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34
Q

which muscles depress the eye

A
  • inferior rectus

- superior rectus

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35
Q

what adducts the eye

A

medial rectus

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36
Q

what abducts the eye

A

lateral rectus

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37
Q

what muscles move the top of the eye towards the nose

A

superior oblique

superior rectus

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38
Q

what muscles move the top of eye away from the nose

A

inferior rectus

inferior oblique

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39
Q

cranial nerve innervation of medial rectus, superior rectus and inferior oblique

A

oculomotor (3)

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40
Q

cranial nerve innervation of superior oblique

A

4- trochlear nerve

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41
Q

cranial nerve innervation of lateral rectus

A

6-abducens

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42
Q

final common pathway of all eye movements

A

brainstem nuclei

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43
Q

which is the most sensitive part of the body with the most nerve endings

A

cornea

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44
Q

what connects the lens to the ciliary body

A

zonules

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45
Q

what allows you to change pupil size

A

muscles in the iris

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46
Q

miosis=

A

pupil constriction

47
Q

miosis nervous control=

A

parasympathetic

48
Q

what is active in miosis

A

iris sphincter

49
Q

mydriasis=

A

pupil dilation

50
Q

what is active in mydriasis

A

iris dilator

51
Q

what nervous controls mydriasis

A

sympathetic

52
Q

what did david bowie have

A

Anisocoria - different levels of pupil dilation

53
Q

accommodation=

A

the process of focusing an image with the lense

54
Q

what looking at a distant object what shape is the lense

A

flat

55
Q

looking at distant objects what position are the eyes in

A

diverge

56
Q

in near objects what do the eyes do

A

converge

57
Q

nervous control of the accommodation reflex-=

A

parasympathetic

58
Q

3 factors of the pupil accommodation reflex

A
  • pupil constriction
  • lens accommodation
  • convergence of the eye
59
Q

what is the most important neural structure in controlling the accommodation reflex

A

Edinger-westphal nucleus (in brainstem)

60
Q

what ganglion do neural impulses to the eye travel in

A

ciliary ganglion

61
Q

most common cause of blindness

A

cataracts

62
Q

cataracts=

A

opacification of the lens caused by compaction and protein deposition

63
Q

name 5 risk factors for cataracts

A 
ageing 
trauma 
diabetes 
smoking 
genetic
64
Q

treatment for cataracts

A

lens removed under local anaesthetic and replaced with artificial lens

65
Q

5 risk factors for glaucoma

A
  • raised intraocular pressure
  • high BP
  • long corticosteroid use
  • severe myopia
  • eye injury
66
Q

2 types of glaucoma

A
  • primary open-angle glaucoma

- acute angle-closure glaucoma

67
Q

cause of primary open-angle glaucoma

A

trabecular meshwork clogged

68
Q

which glaucoma is acute onset

A

acute-angle-closure

69
Q

cause of acute angle closure glaucoma

A

iris bows, closes anterior chamber angle and blocks drainage

70
Q

symptom of primary open-angle glaucoma

A

gradual vision loss (peripheral to central)

71
Q

symptoms of acute angle-closure glaucoma

A

sudden vision loss/ blurring; red eye; severe eye/ head pain; nausea/ vomiting

72
Q

3 tests for glaucoma

A
  • tonometry
  • fundus photography
  • visual perimetry
73
Q

what does tonometry measure

A

intraocular pressure

74
Q

what does fundus photography look at

A

optic nerve

75
Q

visual perimetry=

A

measure visual fields

76
Q

glaucoma treatment (5)

A
  • beta blockers
  • alpha2-adrenoceptor agonist
  • carbonic anhydrase inhibitors
  • prostaglandin analogues
  • miotics (muscarinic agonists)
77
Q

what produces aqueous humour

A

ciliary processes

78
Q

where does the aqueous humour travel

A

passes from the posterior chamber behind the iris through the pupil and into the anterior chamber

79
Q

what drains the aqueous humour

A

trabecular meshwork

80
Q

anterior chamber angle=

A

the angle between the cornea and the iris

81
Q

once the aqueous is through the trabecular meshwork where does it drain

A

schlemm’s canal

82
Q

what blood supply supports the outer retina

A

choroid

83
Q

what blood supply supports the inner retina

A

retinal vasculature

84
Q

only part of the eye without retinal vasculature=

A

fovea

85
Q

outermost layer of the retina=

A

photoreceptors (rods and cones)

86
Q

middle layer of the retina =

A
  • bipolar cells

- amacrine and horizontal cells

87
Q

what do bipolar cells do

A

pass information from the receptors into the ganglion cells

88
Q

what do amacrine and horizontal cells do

A

communication horizontally across the retina

89
Q

what is spread away more in the fovea

A

the first 2 layers (ganglion and bipolar cells)

90
Q

what photoreceptors are presents in the very centre of the retina

A

only cones

91
Q

what are cones good at

A

high resolution vision

92
Q

photoreceptors in the peripheral retina=

A

more rods

93
Q

where are both rods and cones fatter

A

peripheral

94
Q

scotopic photoreceptors=

A

rods

95
Q

scotopic=

A

night time vision (very sensitive to light)

96
Q

photopic=

A

cones

97
Q

photopic=

A 
daytime vision (less sensitive) 
-higher resolution
98
Q

3 types of cones

A

red cones
green cones
blue cones

99
Q

red/green colour blindness is passed down

A

recessively on X chromosome

100
Q

what do protanopes lack

A

red cones

101
Q

what do deuteranopes lack

A

green cones

102
Q

what do tritanopes lack

A

blue cones (NOT X-linked)

103
Q

2 layers of the lateral geniculate nucleus=

A

magnocellular

104
Q

magnocellular=

A

large cells, light/dark greyscale, low resolution

105
Q

4 layers of the lateral geniculate nucleus=

A

parvocellular

106
Q

parvocellular=

A

small cells, higher resolution, colour

107
Q

where is the primary visual cortex

A

back of the brain

108
Q

where are the central visual fields processed in the brain

A

very back of the brain

109
Q

where are the peripheral visual fields processed

A

more anteriorly in the visual cortex

110
Q

where is the brain specialises in colour

A

ventral surface V4

111
Q

where in the brain is sensitive to motion

A

V5 lateral brain

112
Q

sense found in

A

parahippocampal place area

113
Q

faces found in

A

fusiform face area

114
Q

objects found in

A

lateral occipital cortex

Block 12 Ellen (25 decks)

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