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neuro 3rd shift > visual system > Flashcards

visual system Flashcards

1
Q

afferents from eyes to brain

A

CN II - vision and pupillary constriction

CN V - ocular pain, tearing reflex, corneal reflex, proprioception

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2
Q

efferents of eyes

A

CN III, IV, VI - ocular muscles

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3
Q

discuss how light and images pass through eyes and retina

A

light passes through lens and images are inverted and reversed

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4
Q

relate visual spaces to parts of retina

A

upper - lower retina
lower - upper retina

right - left hemiretina
left - right hemiretina

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5
Q

the central fixation point of each eye is at the ______

A

fovea

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6
Q

what represents the fovea

A

half of optic nerve fibers and have of cells of primary visual cortex

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7
Q

the fovea is surrounded by ______

A

macula

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8
Q

discuss all about the optic disc

A

area found 15 deg medial/nasal to fovea and has no photoreceptors

hence blind spot found 15 deg lateral/temporal and inferior to the central fixation point of each eye

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9
Q

discuss all about receptive field

A

receptive field contain photoreceptors that respond to light by forming excitatory or inhib synapses with bipolar cells

bipolar cells synapse with retinal ganglion cells na connected sa optic nerve

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10
Q

discuss the 2 kinds of retinal ganglion cells

A

parasol or A cells - large receptive field; for movement and gross stim; projects to magnocellular layer of LGB

midget or B cells - small receptive field; sensitive and fine vision and color; projects to parvocellular layer of LGB

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11
Q

discuss all about interneurons

A

horizontal and amacrine cells

forms lateral inhibitory or excitatory connection with bipolar and ganglion cells

excitation on part of retina with light inhib on surrounding

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12
Q

discuss all about rods

A

more than cones but poor spatial and temporal resolution; NO COLORS

for low level light - night vision

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13
Q

discuss all about cones

A

less but high in fovea; high spatial and temporal resolution; YES COLORS

for visual acuity

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14
Q

lesions of eye, retina and optic nerve

A

monocular visual field defect

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15
Q

lesions to optic chiasm

A

bitemporal visual field efect

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16
Q

lesions to optic tract, LGB, optic radiations and visual cortex (posterior to optic chiasm)

A

homonymous visual field defects

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17
Q

discuss lateral geniculate nuc and extrageniculate pathways

A

LGB project to primary visual cortex but some enter brachium to go to pretectal area and sup coll

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18
Q

pretectal area is for

A

EDW - pupillary light reflex

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19
Q

sup coll and pretectal is for

A

direct visual attention and eye movements towards stim

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20
Q

what is Meyer’s loop

A

fibers of inferior optic radiation goes to temporal lobes

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21
Q

inferior optic radiations carry info from _______

A

inferior retina - sup visual field

22
Q

upper portions of optic rad projects to ______

A

sup bank of calcarine sulcus

23
Q

temporal lobe lesion

A

contralateral homonymous superior quadrantanopia

24
Q

upper optic radiations pass under ______

A

parietal lobe

25
Q

parietal lobe lesion

A

contralateral homonymous inferior quadrantanopia

26
Q

lesion on calcarine

A

contralateral superior quadrant defects

27
Q

discuss visual processing

A

input arrives at cortical layer 4 of primary visual cortex

sublamin 4A, 4B, 4C alpha and 4C beta

28
Q

sublamina 4B is aka as

A

stria of gennari

29
Q

magnocellular layer of LGB porject to ______

A

to layer 4C alpha

30
Q

parvocellular layer of LGB porject to ______

A

project to 4C beta

31
Q

parvocellular layer and intralaminar zones porject to ______

A

project to cortical layers 2 and 3 - for color

32
Q

purpose of oculomotor system

A

finds, fixates, focuses/aligns on and follows visual targets - foveates

para light will fall on fovea and retinal image falls on corresponding points = visual acuity and single mental image

33
Q

discuss pathway for pupillary contriction

A

light activates ganglion cells - optic nerve - chiasm - tracts - extrageniculate going to pretectal - (B) EDW - ciliary ganglion - ciliary muscles

34
Q

discuss accommodation reflex

A

for near vision - by medial recti so aims eyes near fixation point

contsriction also by pupillary contrictors

lens thickening by ciliary muscles

35
Q

discuss pupillary dilation

A

Postganglionic SY fibers ascend through carotid plexus along the walls of the ICA to cavernous sinus, ultimately reaching the pupillary dilator muscles

36
Q

discuss saccades

A

REM or basta fast vertical or horizontal eye movement

vision transiently suppressed; brings target in field of view

37
Q

discuss smooth pursuit

A

allow stable view of moving objects

retino-geniculo-occipito-parieto-frontaltegmental pathway

38
Q

discuss vergence

A

maintains fused fixation as targets move towards or away

retino-geniculo-occipito-tegmental pathways

39
Q

discuss nystagmus

A

slow eye movement towards wanted direction tas fast movement in opposite

vestibulo-ocular reflex

40
Q

discuss fixation system

A

holds the eyes on the target and promote fusion of both retinal images into one sharp image

retino-geniculo-occipito-tegmental and retinooccipito-fronto-tegmental pathways

41
Q

discuss brainstem circuit for horizontal eye movement

A

by LR and MR - MLF interconnects CN III, IV, VI and CN III nuc for conjugate eye movement in all directions

42
Q

discuss voluntary horizontal eye movements

A

paramedian pontine reticular formation send fibers to ipsi abducens nuc that sends to ipsi LR and contra MR

stimulation of right PPRF or right abducens will make the eyes deviate conjugately to the right

43
Q

discuss brainstem circuit for vertical eye movement

A

by SR, IR, SO and IO

loc in rostral midbrain reticular formation and pretectal area

44
Q

for mediate downgaze

A

Rostral interstitial nucleus of MLF

45
Q

Conjugate upward eye movement

A

tegmentum dorsal downward pathway

46
Q

Conjugate downward eye movement

A

tegmentum dorsomedial to red nucleus

47
Q

saccadic brainstem center for vertical eye movements

A

Rostral interstitial nucleus of the MLF

48
Q

brain stem center for horizontal saccades

A

PPRF

49
Q

discuss role of frontal eye fields or BA 8

A

generate saccades in contralateral direction via connections with contralateral PPRF

50
Q

discuss role of parieto-occipito-temporal cortex

A

for smooth pursuit movements in the ipsilateral direction via connections with vestibular nuclei, cerebellum, PPRF

51
Q

Cortical descending control of eye movements is heavily influenced by visual inputs arriving at the _____

A

primary visual cortex and visual association cortex

52
Q

modulates eye movements

A

basal ganglia

neuro 3rd shift (12 decks)

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