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Neuro Block 7 > Visual System 2 and 3 > Flashcards

Visual System 2 and 3 Flashcards

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
Q

Quadrantanopia

A

Loss of one quarter of a visual field

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26
Q

Homonymous

A

Same field lost in both eyes

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27
Q

Heteronimous

A

Opposite field lost in both eyes

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28
Q

Lesion before the chiasm

A

One eye is affected

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29
Q

Lesion after the chiasm

A

Both eyes are affected

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30
Q

Blind, right eye

A

Optic nerve, embolism from internal carotids

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31
Q

Bitemporal hemianopia

A

Optic tract, pituitary tumor (compresses optic chiasm in the middle)

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32
Q

Left hemianopia, right eye

A

Ischemia, tumor, aneurysm (compresses optic chiasm from the side)

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33
Q

Left homonymous hemianopia

A

Ischemia, tumor, aneurysm (compresses optic chiasm from the side)

34
Q

Left superior quadrantanopia

A

Ischemia or infarct in the temporal lobe (MCA) (affects anterior area of Meyer’s loop)

35
Q

Left homonymous hemianopia

A

Ischemia or infarct in the temporal and occipital lobe (MCA or PCA) (affects both loops)

36
Q

Left inferior quadrantanopia

A

Ischemia or infarct in the parietal or occipital lobe (MCA or PCA, affects superior loops)

37
Q

Left superior quadrantanopia

A

Ischemia or infarct in the temporal or occipital lobe

MCA or PCA, affects inferior loops

38
Q

Inferior loop AKA

A

Meyer’s loop

39
Q

Quadrantanopia with macular sparing

A

Ischemia or infarct affecting superior or inferior optic radiation, macula is spared because it is presented in BOTH parts of the optic radiation

40
Q

Superior radiation affected = ______ quadrantanopia

A

Lower

41
Q

Inferior radiation affected = ______ quadrantanopia

A

Upper

42
Q

Hemianopia with macular sparing is caused by

A

Ischemia or infarct affecting occipital lobe supplied by PCA

43
Q

Why is the macula spared?

A

The region of the occipital lobe where the macula is presented is saved by collaterals coming from the MCA territory

44
Q

Receptor potentials in photoreceptors are the beginning of a neural process in which patterns of light are dissected into their components, which are:

A

Motion, boundaries between light and dark areas, and areas of different color

45
Q

The brain makes its “best guess” in interpreting patterns of light and the results are sometimes

A

Inaccurate or go considerably beyond the information received by the eye

46
Q

Most input to primary visual cortex arrives at cortical layer

A

4

47
Q

Divisions of layer 4

A

Sublaminae 4A, 4B, 4Ca and 4Beta

48
Q

Layer 4B contains numerous

A

Myelinated axon collaterals resulting in the pale-appearing stria of Gennatti

49
Q

Primary visual cortex is also sometimes called

A

Striate cortex

50
Q

From primary visual cortex (area 17), neurons project to

A

the visual association cortex (areas 18 and 19) and other regions of the parieto-occipital and occipitotemporal cortex

51
Q

The dorsal pathways project to

A

Parieto-occipital association cortex

52
Q

The ventral pathways project to

A

Occipitotemporal association cortex

53
Q

The dorsal pathways answer the question _____? by ______

A

Where

By analyzing motion and spatial relationships between objects as well as between the body and visual stimuli

54
Q

The ventral pathways answer the question _____? by ______

A

What

By analyzing form, with specific regions identifying colors, faces, letters, and other visual stimuli

55
Q

The parallel channel layers conveying information about movement and gross spatial features project to

A

Layer 4Ca

56
Q

The parallel channel layers carrying fine spatial information terminate in

A

Layers 4Cb

57
Q

The parallel channel information about color is relayed to

A

Cortical layers 2 and 3

58
Q

Prosopagnosia

A

Patients are unable to recognize people by looking at their faces

59
Q

Lesion that causes prosopagnosia

A

Bilateral inferior occipitotemporal cortex (AKA fusiform gyrus)

60
Q

Some evidence suggests that the _____ hemisphere is more important in facial recognition

A

Right

61
Q

Patients with prosopagnosia cannot recognize people by their faces, but can recognize them based on

A

their clothes, voices, or other cues

62
Q

Agnosia

A

Normal perception but no meaning

63
Q

Hemineglect syndrome

A

Patient perceives only the right half of an object or eats food only on the right half og the plate

64
Q

Normally, the left hemisphere is

A

Aware of the right part of the world around us

65
Q

Normally the right hemisphere is

A

Aware of both sides, with only slight dominance to the left

66
Q

In hemineglect syndrome, the visual fields are affected how?

A

They are intact

67
Q

In hemineglect syndrome, where is the damage?

A

Right hemisphere, right parietal lobe

68
Q

Easy way to test hemineglect syndrome?

A

Draw a line and ask patient to mark the center

69
Q

Amblyopia

A

AKA lazy eye, is decreased vision in an eye that is otherwise normal

70
Q

Whenever the brain does not receive visual signals from an eye for a long period of time, there is a risk of

A

Amblyopia

71
Q

Why does amblyopia occur?

A

The brain turns off the visual processing of one eye to prevent double-vision, the cause is in the brain

72
Q

Detecting what early in childhood increases the chance of successful amblyopia treatment?

A

Strabismus

Especially if before age 5

73
Q

Strabismic amblyopia

A

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
Q

Refractive amblyopia

A

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
Q

Deprivation amblyopia

A

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
Q

Giveaway symptom: sudden vision loss in one eye

A

Embolism

77
Q

Giveaway symptom: veil falling, black curtain

A

Retinal detachment

78
Q

Giveaway symptom: Floaters (dust particles, lint, moving black spots)

A

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
Q

Perception of floaters

A

myodesopsia

80
Q

Pain and redness

A

Acute angle closure glaucoma (increased IOP)
Most often leads to defects in the draining of the intraocular fluid
Emergency - can lead to blindness

81
Q

Redness with watery discharge, both eyes affected

A

Viral conjunctivitis

82
Q

Redness with purulent discharge, one or both eyes affected

A

Bacterial conjunctivitis

Neuro Block 7 (8 decks)

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