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neuroanatomy > Visual Lesion Localization > Flashcards

Visual Lesion Localization Flashcards

1
Q

how do images on the retina form?

A

inverted and reversed
info from the upper visual field is projected on the lower retina, R visual field is project on the L hemiretina

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2
Q

where does the central fixation point fall?

A

on the fovea

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3
Q

what creates the blind spot? where is it located?

A

optic disc
lateral to the macula

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4
Q

what is the visual field?

A

total area seen by the combined visual field of both eyes

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5
Q

how can the retina be divided?

A

by a vertical line, divides fovea and retina into two halves
nasal and temporal

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6
Q

what is the monocular zone?

A

portion of the visual field that comes from only one eye, temporal crescent of the visual field projects to the nasal hemiretina

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7
Q

what decussated in the optic chiasm?

A

visual information from the nasal hemiretinae

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8
Q

what does each optic tract contain?

A

axons from the contralateral nasal hemiretina and ipsilateral temporal hemiretina

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9
Q

stimuli from one visual hemifield are…

A

processed in the contralateral thalamus and cerebral cortex

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10
Q

inferior optic radiations path

A

arc forward from thalamus into the temporal lobe near the inferior horn of the lateral ventricle to lingual gyrus
Meyer’s loop, info from the inferior retina

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11
Q

upper optic radiations path

A

from thalamus, pass under parietal lobe to cuneus gyrus
info from the superior retina

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12
Q

what are the two types of positive visual phenomena?

A

simple and formed

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13
Q

what are examples of simple positive visual phenomena? what are some causes?

A

flashes, lights, colors, shapes
retinal detachment, glaucoma, migraines, occipital seizure

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14
Q

what are examples of formed positive visual phenomena? what are some causes?

A

hallucinations of people/animals, complex scenes
focal seizures, complex migraines, neurodegenerative disorders, toxic disturbances, withdrawal

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15
Q

what do formed positive visual phenomena arise from?

A

inferior occipitotemporal visual association cortex

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16
Q

what is the release phenomenon?

A

formed visual hallucinations in an area of visual field loss

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17
Q

what is a monocular scotoma? where is the lesion?

A

defined region of visual loss in a portion of one eye
retina

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18
Q

what is monocular visual loss? where is the lesion?

A

loss of vision from one entire eye
optic nerve

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19
Q

what is bitemporal hemianopia? where is the lesion?

A

loss of temporal visual fields bilaterally (loss of nasal retina info bilaterally)
optic chiasm

20
Q

what is contralateral homonymous hemianopia? where is the lesion?

A

injury to the same regions of the visual fields for both eyes
optic tract, lateral geniculate nucleus, entire optic radiation, or entire primary visual cortex unilaterally (DGH)

21
Q

what is contralateral superior quadrantanopia? where is the lesion?

A

“pie in the sky”
Meyer’s loop or lower bank of calcarine fissure (EJ)

22
Q

what is contralateral inferior quadrantanopia? where is the lesion?

A

“pie on the floor”
parietal lobe interrupting upper optic radiations or upper bank of calcarine fissure

23
Q

what can result in macular sparing?

A

partial lesions of the visual field because the fovea has a large representation throughout the pathway

24
Q

what can the MCA or PCA do in a lesion of the visual cortex?

A

provide collateral blood supply to the macular region of the visual cortex

25
Q

what is an altitudinal scotoma? where is the lesion?

A

upper or lower retina loss
occlusion one of two major branches of the central retinal artery

26
Q

what can cause binocular altitudinal scotoma?

A

disease of the basilar artery

27
Q

where do a minority of fibers in the optic tracts go?

A

bypass lateral geniculate nucleus to go to the bronchium of the superior colliculus

28
Q

what are projections to the pretectal area* and superior colliculus important for?

A

directing visual attention and eye movements toward visual stimuli
pupillary light reflex*

29
Q

where does the pretectal area and superior colliculus project to?

A

association cortex via relays in the pulvinar and lateral posterior nucleus of thalamus

30
Q

the pupillary light reflex is under what type of control

A

parasympathetic

31
Q

pupillary light reflex pathway

A

light activates retinal ganglion cells, project to both optic tracts to brachium of superior colliculus, synapse in pretectal area
axons project bilaterally to Edinger-Westphal nucleus synapse on preganglionic parasympathetic neuron
pregang fibers travel bilaterally in CN III to synapse on postgang para neurons in the ciliary ganglion
postgang fibers to pupillary constrictor muscles

32
Q

direct vs consensual response

A

direct - same eye with light shone in it
consensual - opposite eye

33
Q

pupil dilation is under what kind of control?

A

sympathetic

34
Q

pupil dilation pathway

A
35
Q

dorsal visual processing pathway

A

“where?” pathway to parieto-occipital association cortex
motion and spatial relationships between objects and self

36
Q

ventral visual processing pathway

A

“what?” pathway to occipitotemporal association cortex
analyzing form, with specific regions for colors, faces, letters

37
Q

cortical blindness

A

bilateral damage to primary visual cortex
lack insight into disease (anosognosia)
dismiss diagnosis, confabulate visions

38
Q

what can inferior occipitotemporal cortex damage cause?

A

prosopagnosia, achromatopsia, micropsia

39
Q

what is Balint’s syndrome?

A

bilateral damage to dorsolateral parieto-occipital cortex
simultanagnosia, optic ataxia, ocular apraxia

40
Q

prosopagnosia

A

inability to recognize faces, bilateral fusiform gyrus damage

41
Q

achromatopsia

A

central disorder of color perception; can’t name, point to, or match colors presented visually
can name/recall appropriate color of objects verbally

42
Q

micropsia

A

objects appear unusually small or large

43
Q

simultanagnosia

A

impaired ability to perceive parts of a visual scene as a whole; perceived area shifts unpredictably

44
Q

optic ataxia

A

impaired ability to reach for or point to objects under visual guidance; proprioception is intact though, can reach for an object once it has been touched

45
Q

ocular apraxia

A

difficulty voluntarily directing one’s gaze toward objects in the periphery through saccades

neuroanatomy (14 decks)

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