Vision (for eye antomy see eye and ear deck in anatomy) Flashcards

1
Q

what is accomodation

A

adjustment of the lens in the eye so clear images of objects at different distances are formed on the retina

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2
Q

what refracts light entering the eye

A

cornea (2/3)

lens (1/3)

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3
Q

where is light focused onto

A

retin

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4
Q

what regulates the shape of the lens

A

ciliary muscles

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5
Q

what does sympathetic stimulation of the ciliary muscles do

A

relaxes them

flattened and weak lens - less light bending

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6
Q

what does parasympathetic stimulation of the ciliary muscles do

A

contracts ciliary muscles
accomodation
rounded, strong lens - more light bending

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7
Q

what makes up the wall of the eyeball

A

fibrous sclera and cornea
choroid, iris and ciliary body (uvea)
retina (rods and cones)

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8
Q

what are the 2 cavities of the eye

A

anterior and posterior

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9
Q

describe the posterior cavity

A

separated from anterior cavity by the lens

filled with vitreous humour

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10
Q

what separates the anterior and posterior cavity

A

lens

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11
Q

describe the anterior cavity

A

separated from posterior cavity by the lens
divided into anterior and posterior CHAMBER by the iris
contains aqueous humour

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12
Q

what controls the size of the pupil

A

iris

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13
Q

what are the 2 muscles associated with the iris

A

sphincter and dilator

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14
Q

what does parasympathetic stimulation if the iris do

A

pupillary constriction

sphincter contraction

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15
Q

what does sympathetic stimulation of the iris do

A

pupillary dilation

dilator constriction

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16
Q

where is the ocular blood supply from

A
ophthalmic artery (from internal carotid)
branches - most impoatant is central retina artery (supplies retina)
17
Q

where is the primary visual cortex

A

occipital lobe calcarine sulcus

18
Q

what is the function of the visual association cortex

A

interpreting visual images, recognition, depth perception, colour vision

19
Q

where is the visual association cortex

A

surrounds primary visual cortex (in calcarine sulcus)

20
Q

describe light transmission from temporal visual field

A
  • temporal visual field goes to nasal portion of retina
  • optic nerve carries axons of cells in ganglionic layer of retina
  • leave orbit via optic canal and enter cranial cavity
  • nasal portion fibres cross at optic chiasm
  • optic tracts carry fibres posteriolaterally around cerebral peduncles
  • terminate at lateral geniculate body of thalamus
21
Q

describe Baum’s loop

A

parietal lobe
superior loop
carries fibres from INFERIOR visual field (so superior part of retina)

22
Q

describe Meyer’s loop

A

Temporal lobe
lateral loop
carries fibres from SUPERIOR visual field (so inferior portion of retina)

23
Q

what would cause a left homonymous hemianopia

A

defect in left optic nerve

24
Q

what would cause a bitemporal hemianopic

A

problem in optic chiasm

25
Q

which fibres cross at the optic chiasm

A

from temporal visual field = nasal part of retina

26
Q

what would cause a left nasal and right temporal hemianopia

A

problem in left optic tract

27
Q

what would cause a right upper /(contralateral) homonymous superior quadrantanopia

A

problem in left Meyer’s loop (temporal lobe, lateral loop)

28
Q

what would cause a right lower/ contralateral homonymous inferior quadrantanopia

A

problem in left Braun’s loop (parietal lobe, superior loop)

29
Q

what would cause a left nasal and right temporal hemianopia with macula sparing

A

problem in optic radiation