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DPT 520 > The Visual System > Flashcards

The Visual System Flashcards

1
Q

what is required for control of eye movement?

A

visual stimuli

sensory info from eye muscles

head movement (direction, velocity)

auditory info (via sup colliculus)

limbic system (fear, excitement)

voluntary control (intention, plan)

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2
Q

what are the fxns of the visual system?

A

control eye movement

visual ID of objects

perception of the relationships bw objects and self

contribute to motor control

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3
Q

what muscles control the thickness of the lens?

A

ciliary muscles

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4
Q

when the lens is contracted is it thicker or thinner and does this allow for near or far vision?

A

when the lens is contracted, it’s thicker and allows for near vision

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5
Q

what is the optic disk?

A

blind spot

where all the ganglionic neurons are bundled and leave the eye

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6
Q

what is the fovea?

A

the area of the retina w/the most rods and cones for best visual acuity

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7
Q

describe the image of the retina?

A

inverted and flipped

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8
Q

where is the 4th quadrant (lower R) of the visual field in the retinal image

A

upper L

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9
Q

where is the 3rd quadrant (lower L) of the visual field in the retinal image?

A

upper R

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10
Q

where is the 2nd quadrant (upper R) of the visual field in the retinal image?

A

lower L

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11
Q

where is the 1st quadrant (upper L) of the visual field in the retinal image?

A

lower R

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12
Q

what is the 1st order neuron of the visual input from the retina to the cortex?

A

optic nerve

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13
Q

what is the path of the 1st order neuron for visual input?

A

optic chiasm–>optic tract–> lateral geniculate nucleus of the thalamus

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14
Q

what is the path of the second order for visual input

A

LGN–>optic radiation (geniculocalcarine tract)–>primary visual cortex (V1)

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15
Q

what is V1 responsible for?

A

conscious vision

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16
Q

what is another name for the V1 cortex?

A

calcarine cortex

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17
Q

what structures make up the midbrain?

A

tectum, pretectum, and superior colliculus

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18
Q

what is the visual fxn of the midbrain?

A

pupillary reflexes and orienting the eyes and head

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19
Q

what are the 2 streams that come from the V2 cortex?

A

dorsal action stream

ventral perception stream

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20
Q

what is the V2 cortex responsible for?

A

color and motion

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21
Q

what is the dorsal stream

A

the action stream

visual guidance for movement

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22
Q

what is the ventral stream?

A

the perception stream

visual ID of the object

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23
Q

where does the dorsal action stream flow?

A

to the posterior parietal cortex

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24
Q

where does the ventral perception stream flow?

A

to the occipitotemporal region

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25
Q

does the nasal or temporal retina cross the midline in the optic chiasm?

A

the nasal retina

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26
Q

does the nasal or temporal retina remain ipsilateral

A

the temporal retina

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27
Q

t/f: info from one visual field projects to the opposite visual cortex

A

true

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28
Q

where does light from the R visual field go to?

A

the nasal retina on the R

the temporal retina on the L

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29
Q

all axons leaving the chiasm in the L optic tract carry info from the __ visual field–> __ LGN–>__ V1 cortex

A

R, L, L

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30
Q

all axons leaving the chiasm in the R optic tract carry info from the __ visual field–>__ LGN–>__ V1 cortex

A

L, R, R

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31
Q

are visual pathway lesion named by the side you can or can’t see out of?

A

the side you CAN’T see out of

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32
Q

what is the visual loss with a R optic nerve lesion?

A

R monocular vision loss

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33
Q

what is bitemporal (heteronomous) hemianopsia?

A

loss of the medial retinal images and lateral visual field

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34
Q

if there is a loss of the medial retinal image, what is the loss in the visual field?

A

lateral

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35
Q

if there is a loss of the lateral retinal image, what is the loss in the visual field?

A

medial

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36
Q

what visual loss with an optic tract lesion?

A

homonymous hemianopsia

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37
Q

what is homonymous hemianopsia?

A

loss of the same side in both eyes

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38
Q

what is quadrantopsia?

A

loss of a quadrant of the vision that can be superior or inferior

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39
Q

what is the Edinger-Westphal nucleus?

A

the nucleus of CN 3 parasympathetic neurons (efferent of oculomotor reflexes) in the midbrain tegmentum

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40
Q

what are the oculomotor reflexes?

A

pupillary light reflex

accomodation reflex

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41
Q

what muscles are innervated by the neurons from the Edinger Wesphal nucleus?

A

pupillary sphincter and ciliary muscles

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42
Q

what is the pupillary light reflex?

A

light is shone in one eye and the pupils constricts in both eyes

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43
Q

what is the afferent of the pupillary light reflex? efferent?

A

afferent=CN 2
efferent=CN 3

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44
Q

what happens in ipsilateral direct pupillary light reflex when a light is shone in the L eye?

A

the L pretectal area receives the info and activates the L CN 3 parasympathetic nucleus

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45
Q

what happens in the indirect consensual pupillary light reflex when a light is shone in the L eye?

A

the L pretectal area receive the info and activates the R CN parasympathetic nucleus

info goes bilaterally

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46
Q

if there is a lesion to the R optic nerve, and a light is shined in the R eye, what is the direct response? consensual response?

A

no direct or consensual response

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47
Q

if there is a lesion to the L optic nerve, and a light is shined in the R eye what is the direct response? consensual response?

A

normal direct and consensual response

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48
Q

if there is a R oculomotor nerve lesion and a light is shined in the R eye, what is the direct response? consensual response?

A

absent direct response, normal consensual response

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49
Q

if there is a L oculomotor nerve lesion and a light is shined into the R eye, what is the direct response? consensual response?

A

normal direct response, absent consensual response

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50
Q

what is the near triad?

A

adjustment for near vision to maintain clarity of images at the fovea

1) accomodation reflex
2) pupillary constriction
3) convergence

51
Q

is convergence conjugate or dysconjugate eye movement?

A

dysconjugate

52
Q

what is the accomodation reflex?

A

the lens thickens from contraction of the ciliary muscles to adjust to near objects

53
Q

what is the pathway of the accomodation reflex?

A

visual cortex–>oculomotor nuclei (midbrain)–>ciliary muscle

54
Q

what is the pathway of pupillary constriction?

A

visual cortex–>oculomotor nuclei–> sphincter muscle

55
Q

what is dysconjugate eye movement?

A

eyes moving in opposite directions

56
Q

what is conjugate eye movement?

A

eyes moving in the same directions

57
Q

what is the pathway for convergent eye movement?

A

visual cortex–>frontal eye fields –>CN 3

58
Q

what are the age related pupillary changes?

A

pupils become smaller and sluggish

older adults can take more than 40 minutes to adjust to darkness

less flexible adjustment of the lens

59
Q

what causes blown pupils?

A

CN 3 isn’t working to constrict the pupil bc the sphincter muscles aren’t innervated, so it stays dilated

efferent pupillary reflex isn’t working

increased intracranial pressure

BS damage

60
Q

what causes miosis (excessive constriction)?

A

Horner’s syndrome

drug overuse

61
Q

t/f: binocular vision requires image projection to corresponding point on both retinas

A

true

62
Q

if image projection is not lined up in both eyes what occurs?

A

double vision

63
Q

what structure is really important in L/R eye movement control?

A

the MLF!

64
Q

how does the sup colliculus contribute to L/R eye movement?

A

via the MLF

65
Q

what is the job of the MLF?

A

signals for head-eye movement coordination

BL connections among CN 3, 4, 6, 8, 11 nuclei

66
Q

what is the result of an MLF lesion?

A

internuclear opthalmoplegia (INO) - lesion in the connection bw CN 3 and 6 contralaterally

can’t adduct one eye

eyes aren’t lined up=diploplia

67
Q

what muscles need to be activated for conjugate eye movement?

A

lateral rectus and medial rectus

68
Q

what muscles does CN 3 innervate?

A

levator palpebrae superioris

sup rectus

med rectus

inf rectus

inf oblique

pupillary sphincter muscles

ciliary muscles

69
Q

what muscles are innervated by CN 4?

A

superior oblique

70
Q

what muscles are innervated by CN 6?

A

lateral rectus

71
Q

what is the role of the sup rectus?

A

eyes up

72
Q

what is the role of the med rectus?

A

eyes medially

73
Q

what is the role of the inf rectus?

A

eyes down

74
Q

what is the role of the inf oblique?

A

moves adducted eye up and rotates abducted eye

75
Q

what is the role of the sphincter muscles?

A

pupillary constriction

76
Q

what is the role of the ciliary muscles?

A

increases the curvature of the lens of the eye

77
Q

what is the role of the superior oblique?

A

brings the adducted eye down and rotates the abducted eye

78
Q

what is the role of the lat rectus?

A

eye laterally

79
Q

what is the result of a CN 3 lesion?

A

ipsilateral eye deviation out and down (can’t look in and up)

ptosis (droopy eyelid)

loss of pupillary constriction (enlarged pupil)

80
Q

what is the result of a CN 4 lesion?

A

ipsi eye deviates up when adducted

no upward deviation unless adducted

81
Q

what is the result of a CN 6 lesion?

A

ipsi eye deviates inward

eye can’t abduct bc of abducens and lateral rectus lesion

82
Q

a lesion to what CNs can lead to diploplia?

A

CN 3, 4, 6

83
Q

what causes diploplia?

A

misalignment of the eyes

84
Q

will a chronic lesion have diploplia?

A

no, only acute, bc in chronic the eye will learn to block out images of one side

85
Q

t/f: there is a loss of depth perception in chronic lesion bc of the lack of 2 visual fields

A

true

86
Q

does a CN 3 lesion result in horizontal or vertical diploplia?

A

can be either or both

87
Q

does a CN 4 lesion result in horizontal or vertical diploplia?

A

vertical (bc one eye is higher)

88
Q

does a CN 6 lesion result in horizontal or vertical diploplia?

A

horizontal

89
Q

does INO result in vertical or horizontal diploplia?

A

horizontal (bc one eye can’t abduct)

90
Q

what is vertical diploplia?

A

eye is deviated upward and makes taking stairs difficult

91
Q

what is horizontal diploplia?

A

eye deviated R/L makes it difficult to read

92
Q

what are the 2 objects of eye movement?

A

direction of gaze and gaze stabilization

93
Q

what are the components of direction of gaze?

A

saccades

smooth pursuits

vergence

94
Q

what are saccades?

A

look quickly bw 2 images

95
Q

what are smooth pursuits?

A

following slow motion like a moving train

tracking motions

96
Q

what is vergence?

A

dysconjugate eye movements

97
Q

what are the components of gaze stabilization?

A

VOR and OKR (optokinetic reflex)

98
Q

what is the optokinetic reflex (OKR)?

A

physiologic/normal nystagmus

rapid eye movements

99
Q

what are reflexive saccades?

A

unexpected movement mediated by the superior colliculus

100
Q

what are voluntary saccades?

A

saccades involving more brain structures

frontal eye fields–> sup colliculus–> pons (PGC) and midbrain reticular formation–>CN 6, 3, 4

101
Q

horizontal saccades result from stimulus from what CNs?

A

6 then 3

102
Q

vertical saccades result from stimulus from what CNs?

A

3 and 4

103
Q

what structures are involved in horizontal smooth pursuits?

A

CN 6 and part of CN 3

104
Q

what structures are involved in vertical smooth pursuits?

A

midbrain reticular formation

CN 3 and 4

105
Q

is smooth pursuits or saccades examined more by PTs?

A

smooth pursuits

106
Q

what is the pathway for horizontal smooth pursuits?

A

visual cortex–>temporal eye fields–>frontal eye fields–> dorsolateral pons–>vestibular cerebellum–>vestibular nuclei–> CN 6 then 3

107
Q

what is the pathway for vertical smooth pursuits?

A

visual cortex–>temporal eye fields–>frontal eye fields–> dorsolateral pons–>vestibular cerebellum–>vestibular nuclei–> midbrain reticular formation–> CN 3 and 4

108
Q

what is nystagmus?

A

involuntary oscillating eye movement

physiologic or pathologic

109
Q

what is the pathway of the optokinetic reflex?

A

pretectal area–>med vestibular nuclei–> oculomotor nuclei

110
Q

what is vection? what is it important in?

A

illusion of movement/sensation of movement of the body in space produced by visual stim

VR games

111
Q

is OKR physiologic or pathologic nystagmus?

A

physiologic

112
Q

what are the 2 components of the OKR?

A

saccades and smooth pursuits

113
Q

what does the VOR do?

A

stabilizes gaze on a target during fast head movement

114
Q

when the head moves in one direction, which direction do the eyes move?

A

in the opposite direction

115
Q

what is the pathway for the VOR?

A

head rotation–>SCC–>vestibular nuclei–>MLF–>oculomotor nuclei–>extraocular muscles

116
Q

when the head rotates right, what extraocular muscles are activated?

A

lat rectus on the L

med rectus on the R

117
Q

which visual stream is essential for saccades?

A

dorsal (action) stream

118
Q

what are the areas essential for saccades?

A

frontal eye fields

dorsolateral prefrontal cortex

post parietal cortex

119
Q

what are the frontal eye fields responsible for?

A

voluntary control of eye movements

120
Q

what is the dorsolateral prefrontal cortex (DLPFC) responsible for?

A

preparation of saccadic eye movement

121
Q

what is the post parietal cortex responsible for?

A

spatial info for eye movement

122
Q

what visual stream is essential for the OKR and smooth pursuits?

A

ventral (perceptual) stream

123
Q

what structures are essential for the OKR and smooth pursuits?

A

occipital and temporal eye fields

DPT 520 (13 decks)

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