The visual system Flashcards

1
Q

what are the only cells in the retina that produce nerve impulses?

A

retinal ganglion cells(projection neurons)

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2
Q

what are the only cells that have projections that leave the eye?

A

retinal ganglion cells(projection neurons)

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3
Q

what neurons process light?

A

internal nuclear cell layer

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4
Q

what do amacrine cells and horizontal cells do?

A

talk with multiple streams of information and provide contrast in the visual field.
eg: being able to detect edges

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5
Q

what do rods and cones do?

A

phototransduction, grated potentials

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6
Q

what cell spans the retina and provides ion support and makes the virtuous humor? It is the only glial cell as well

A

muller supporting cell

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7
Q

what cells are the only cells that us an action potential in the retina?

A

the retinal ganglion cells the rest use graded potentials

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8
Q

what is the fovea used for?

A

high acuity vision, highest amount of cones are here

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9
Q

where are rods located?

A

just outside the fovea

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10
Q

what happens are the chiasm?

A

a partial decussation

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11
Q

axons for temporal visual fields (lateral) do what at chiasm?

A

cross the contralateral

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12
Q

axons for the nasal visual vision (medial) do what at chiasm?

A

remain ipsilateral

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13
Q

the optic tract projects to what struction in the thalamus?

A

lateral geniculate nucleus (LGN)

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14
Q

secondary neurons from the lateral geniculate nucleus go where?

A

to the primary visual cortex via optic radiations

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15
Q

where is the superior field of vision located in the optic radiations?

A

in the temporal portion called the meyes loop

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16
Q

where is the inferior field of vision located in the optic radiations?

A

in the parietal part

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17
Q

what does pie in the sky mean?

A

damage to meyers loop will result in losing the superior vision

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18
Q

primary visual cortex is divided into two portions, what are they?

A

lower field which is above the upper field

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19
Q

what is the macula?

A

where high acuity vision goes

20
Q

what is the calcarine sulcus

A

what divides the lower and upper fields gyrus in the primary visual cortex

21
Q

the retinal is supplied by what artery?

A

ophthalmic artery

22
Q

the optic tract and lateral geniculate nucleus is supplied by what artery?

A

anterior choroidal artery(branch of middle cerebral)

23
Q

what parietal optic radiations are supplied by what artery?

A

middle cerebral

24
Q

the calcarine cortex is supplied by what artery?

A

posterior cerebral artery from the basilar artery

25
in the pupillary light reflex the retinal ganglion cells send axons to what nucleus?
pretectal region
26
axons from the pretectal region nucleus go where?
to the EW nucleus
27
from the EW nucleus where do the parasympathetic axons go?
to the ciliary ganglion
28
the nerve axons from the ciliary ganglion then go where?
to the pupillary constrictor muscles
29
is the pupillary light reflex consensual?
yes
30
subdural hematoma with uncal herniation symptoms
sluggish or absent pupillary reflex ptosis less effects on extraocular movements CNIII effects
31
pupillary dilation sympathetic pathway 1st step
hypothalamus sends signal to T1 sympathetics
32
from the T1 level where does the sympathetic axon go?
to the superior cervical ganglion
33
from the superior cervical ganglion where do the axons go?
to the pupil | tarsal muscle
34
symptoms of horner's syndrom
ptosis miosis anhyrosis PAM has horns
35
a lesion any where on the sympathetic pathway will lead to horner's syndrome T/F?
true
36
what does it mean that eyes are yoked?
move the same direction controlled by centers in cortex and brainstem no direct path from upper motor neurons to cranial nerves
37
frontal eye fields do what?
voluntary fast horizontal eye movements of the opposite eye.
38
what is the PPRF?
paramedian pontine reticular formation
39
cells in the frontal eye field project to contralateral PPRF T/F
true
40
where does the crossing occur ?
cuadal to nucleus III
41
what does the PPRF do?
coordiates horizontal movements between CN III, IV, VI for both eyes
42
from the PPRF where do axons go?
to the CN VI nucleus
43
from CN VI where do the axons go?
to the lateral rectus and to CN III nucleus
44
when axons from CN VI go the CN III nucleus what does it do?
synapses only on the medial rectus neurons
45
PPRF lesions lead to horizontal gaze paralysis of both eyes, toward the side of the lesion or to the opposite side of lesion?
to the same side
46
what is the MLF
the neuron going from CN VI nucleus to CN III nucleus
47
a lesion of the MLF leads to what?
loss of adduction in ipsilateral eye. diplopia(double vision) typically a sign of MS ***other CN III functions are unaffected**