Visual System 2 and 3 Flashcards

(82 cards)

1
Q

Ganglion cell axons travel in the ______ to the ______

A

Optic nerve

Optic chiasm

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2
Q

At the level of the optic chiasm, axons coming from the lateral retina

A

DO NOT DECUSSATE and enter the IPSILATERAL optic tract

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3
Q

At the level of the optic chiasm, axons coming from the medial retina

A

DECUSSATE and enter the CONTRALATERAL optic tract

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4
Q

Fibers in each optic tract terminate in the

A

Lateral geniculate nucleus (the thalamic relay nucleus for vision) FIRST ORDER NEURONS

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5
Q

Geniculate fibers travel through the internal caps and corona radiate to

A

the primary visual cortex in the banks of the calcarine sulcus

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6
Q

A minority of fibers in the optic tract bypass the LGN to enter the

A

Brachium of the superior colliculus

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7
Q

Fibers that enter the brachium of the superior colliculus form the extrageniculate visual which mainly project to the

A

Pretectal area and superior colliculus

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8
Q

The pretectal area is important in the

A

Pupillary light reflex

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9
Q

The superior colliculus and pretectal area are also involved in

A

Directing eyes towards visual stimuli

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10
Q

Fibers arising from the lateral geniculate nucleus (2nd order) curve around the lateral wall of the lateral ventricle as

A

Optic radiation

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11
Q

Optic radiation terminates

A

In the cortex adjacent to the calcarine sulcus

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12
Q

Optic radiation covers

A

Much of the posterior and inferior horns od the lateral ventricle

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13
Q

Fibers representing superior retivisual quadrants loop our into the ______ before turning posteriorly

A

Temporal

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14
Q

Upper retina projects to cortex

A

Above calcarine sulcus

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15
Q

Lower retina projects to cortex

A

Below calcarine sulcus

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16
Q

Macula projects to cortex

A

Middle area, posteriorly

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17
Q

Lesions where often cause visual loss in one quadrant of the visual field with MACULAR SPARING

A

Optic radiation

GIVEAWAY FOR OCCIPITAL LOBE

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18
Q

Peripheral fields project to cortex

A

Anteriorly

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19
Q

What represents a large area of the primary visual cortex?

A

Macula

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20
Q

Blood supply of optic radiations

A

Branches of middle cerebral arteries that penetrate deep into white matter

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21
Q

Blood supply of visual cortex

A

Posterior cerebral cortex

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22
Q

Visual field defects are named according to

A

Visual field loss and NOT according to the area of the retina or optic pathway that is nonfunctional

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23
Q

Blindness

A

Loss of the whole visual field

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24
Q

Hemianopia

A

Loss of half a visual field

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25
Quadrantanopia
Loss of one quarter of a visual field
26
Homonymous
Same field lost in both eyes
27
Heteronimous
Opposite field lost in both eyes
28
Lesion before the chiasm
One eye is affected
29
Lesion after the chiasm
Both eyes are affected
30
Blind, right eye
Optic nerve, embolism from internal carotids
31
Bitemporal hemianopia
Optic tract, pituitary tumor (compresses optic chiasm in the middle)
32
Left hemianopia, right eye
Ischemia, tumor, aneurysm (compresses optic chiasm from the side)
33
Left homonymous hemianopia
Ischemia, tumor, aneurysm (compresses optic chiasm from the side)
34
Left superior quadrantanopia
Ischemia or infarct in the temporal lobe (MCA) (affects anterior area of Meyer's loop)
35
Left homonymous hemianopia
Ischemia or infarct in the temporal and occipital lobe (MCA or PCA) (affects both loops)
36
Left inferior quadrantanopia
Ischemia or infarct in the parietal or occipital lobe (MCA or PCA, affects superior loops)
37
Left superior quadrantanopia
Ischemia or infarct in the temporal or occipital lobe | MCA or PCA, affects inferior loops
38
Inferior loop AKA
Meyer's loop
39
Quadrantanopia with macular sparing
Ischemia or infarct affecting superior or inferior optic radiation, macula is spared because it is presented in BOTH parts of the optic radiation
40
Superior radiation affected = ______ quadrantanopia
Lower
41
Inferior radiation affected = ______ quadrantanopia
Upper
42
Hemianopia with macular sparing is caused by
Ischemia or infarct affecting occipital lobe supplied by PCA
43
Why is the macula spared?
The region of the occipital lobe where the macula is presented is saved by collaterals coming from the MCA territory
44
Receptor potentials in photoreceptors are the beginning of a neural process in which patterns of light are dissected into their components, which are:
Motion, boundaries between light and dark areas, and areas of different color
45
The brain makes its "best guess" in interpreting patterns of light and the results are sometimes
Inaccurate or go considerably beyond the information received by the eye
46
Most input to primary visual cortex arrives at cortical layer
4
47
Divisions of layer 4
Sublaminae 4A, 4B, 4Ca and 4Beta
48
Layer 4B contains numerous
Myelinated axon collaterals resulting in the pale-appearing stria of Gennatti
49
Primary visual cortex is also sometimes called
Striate cortex
50
From primary visual cortex (area 17), neurons project to
the visual association cortex (areas 18 and 19) and other regions of the parieto-occipital and occipitotemporal cortex
51
The dorsal pathways project to
Parieto-occipital association cortex
52
The ventral pathways project to
Occipitotemporal association cortex
53
The dorsal pathways answer the question _____? by ______
Where By analyzing motion and spatial relationships between objects as well as between the body and visual stimuli
54
The ventral pathways answer the question _____? by ______
What By analyzing form, with specific regions identifying colors, faces, letters, and other visual stimuli
55
The parallel channel layers conveying information about movement and gross spatial features project to
Layer 4Ca
56
The parallel channel layers carrying fine spatial information terminate in
Layers 4Cb
57
The parallel channel information about color is relayed to
Cortical layers 2 and 3
58
Prosopagnosia
Patients are unable to recognize people by looking at their faces
59
Lesion that causes prosopagnosia
Bilateral inferior occipitotemporal cortex (AKA fusiform gyrus)
60
Some evidence suggests that the _____ hemisphere is more important in facial recognition
Right
61
Patients with prosopagnosia cannot recognize people by their faces, but can recognize them based on
their clothes, voices, or other cues
62
Agnosia
Normal perception but no meaning
63
Hemineglect syndrome
Patient perceives only the right half of an object or eats food only on the right half og the plate
64
Normally, the left hemisphere is
Aware of the right part of the world around us
65
Normally the right hemisphere is
Aware of both sides, with only slight dominance to the left
66
In hemineglect syndrome, the visual fields are affected how?
They are intact
67
In hemineglect syndrome, where is the damage?
Right hemisphere, right parietal lobe
68
Easy way to test hemineglect syndrome?
Draw a line and ask patient to mark the center
69
Amblyopia
AKA lazy eye, is decreased vision in an eye that is otherwise normal
70
Whenever the brain does not receive visual signals from an eye for a long period of time, there is a risk of
Amblyopia
71
Why does amblyopia occur?
The brain turns off the visual processing of one eye to prevent double-vision, the cause is in the brain
72
Detecting what early in childhood increases the chance of successful amblyopia treatment?
Strabismus Especially if before age 5
73
Strabismic amblyopia
Most common, to avoid double vision caused by poorly aligned eyes, the brain ignores visual input from the misaligned eye, leading to amblyopia in that eye
74
Refractive amblyopia
Caused by unequal refractive errors in the two eyes despite perfect eye alignment (ie. severe hyperopia or myopia in one eye, or astigmatism in one and not in the other) so the brain relies on the eye that has less uncorrected refractive error and "tunes out" the blurred vision from the other eye, causing amblyopia from disuse
75
Deprivation amblyopia
Caused by something that obstructs light from entering and being focused in a baby's eye (like a congenital cataract) Prompt treatment of congenital cataracts is necessary to allow normal visual development to occur
76
Giveaway symptom: sudden vision loss in one eye
Embolism
77
Giveaway symptom: veil falling, black curtain
Retinal detachment
78
Giveaway symptom: Floaters (dust particles, lint, moving black spots)
deposits of various size, shape, consistency, refractive index, within the vitreous humor, which is normally transparent Develop with age due to degenerative changes of the vitreous
79
Perception of floaters
myodesopsia
80
Pain and redness
Acute angle closure glaucoma (increased IOP) Most often leads to defects in the draining of the intraocular fluid Emergency - can lead to blindness
81
Redness with watery discharge, both eyes affected
Viral conjunctivitis
82
Redness with purulent discharge, one or both eyes affected
Bacterial conjunctivitis