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Neuro Anatomy > Test 2: Visual > Flashcards

Test 2: Visual Flashcards

1
Q

What CN does vision

A

CN II- optic nerve

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2
Q

Why is CNII NOT a peripheral nerve?

A

retinal structure from diencephalon development

myelinated neurons with oligodendycytes-CNS

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3
Q

What is the pathway of light traveling into the eye?

A

Iris through lens to retina- focused on fovea to optic nerve

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4
Q

What does the pupillary constrictor muscle do?

A

controls amount of light entering the eye via controlling the iris

  • parasympathetic constricts
  • synpathetic relaxes
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5
Q

What do ciliary muscles do?

A

adjusts lens thickness to help bend light to focal point (fovea)

  • visual accomodation
  • paraysmp: thickens
  • sympathetic relaxes
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6
Q

What is the retina? what’s in it?

A

has visual receptors lining the walls of the eye

  • macula on posterior wall= increase density
  • fovea in macula= highest density of cones
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7
Q

What is the optic disk? what’s in it?

A

blind spot

  • axons from retina and vasculature exit through here
  • vascular from internal carotid-opthalamic vessels
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8
Q

What makes up the fovea?

A

5 types of neurons

  • mainly photoreceptors= rods and cones
  • retinal ganglia cells

Everything flipped upside down!!

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9
Q

What are rods?

A

photoreceptor in fovea

  • ALL wavelengths visible light
  • dense around macula
  • detects light levels and motion– course vision
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10
Q

What are cones?

A

photreceptor in fovea

  • 3 types of pigements to transduce color wavelenths: red, green, blue
  • most dense around fovea where macula has greatest visual acquity
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11
Q

What are retinal ganglia?

A

output neurons- 1CB of visual pathway

  • axons collect at optic disk and once exit eye all travel as CNII
  • unmeylinated axons until exit disk-> myelinated with oligodend
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12
Q

What are pigment epitheliums? what are the 3 types?

A

melanin that absorbs light to decrease scatter

  1. opesins: photo pigment for color
  2. rodespin: light/dark
  3. melanopsin: special ganglia with melanin
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13
Q

What are the 4 possible pathways of visual perception?

A
  1. Primary pathway-> V1
    - occipital pole
  2. Suprachiasm nucleus of hypothal
    - diurnal clock
    - light/dark
    - melanopsin
  3. Pretectal nuclei (midbrain)
    - pupil constrictor/thicken lens
    - parasympathetic reflexes
  4. Superior colliculus (midbrain)
    - eye movements relative to environment
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14
Q

What is the 1neron characteristic of the Primary Visual pathway?

A

axons off of photoreceptors

  • collect/sort 3 regions of projections
  • all axons travel in ipsilateral optic nerve
  • enter chiasm: vulnerable to pituitary tumor damage

Nasal: 60% decussate in chiasm-> contrlateral optic tract
Temporal: 40% stay ipsilateral-> ipsilateral optic tract

Tracts-> LGN -> internal capsule -> optic radiations -> VI

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15
Q

What is the BA number of V1

A

BA 17

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16
Q

What are the layers of the LGN

A

4 parvocellar layers: show color

2 magnocellar layers: percieve motion

17
Q

What is the striate cortex?

A

superior and inferior banks by calcacrine sulcus

Inferior visual field goes up through parietal to SUP bank

Superior visual field goes down through temporal to INF bank
-some bend around inferior horn of lateral ventricles= Meyers loop

18
Q

What is the monocular visual field?

A

Vision of one eye
-seperate into 4 quadrants: superior, inferior, nasal, and temporal

TEMP CRESCENTS 930 deg) project to NASAL retina

19
Q

What is the binocular visual field?

A

Detected by both eyes
-majority of visual field except small monocular temporal crescents

MOST (90 deg) projects to BILAT TEMPORAL retina

20
Q

What do the extraocular muscles do in relationship to convergence?

A

control eye alignment- focul point on fovea

-converge to fovea to get optimal visual acuity

21
Q

How does the light refract through lens and in brain?

A

Inverted through lens onto retina

  • inferior field on top
  • superior field on bottom

L and right fields are flipped
-temporal visual field of L eye projects to nasal retina of left eye

22
Q

Where do the R visual fields project in the brain?

A

LEFT V1

23
Q

What does damage to the L eye/optic nerve result in?

A

Ipsilateral blindness

  • can’t see from L eye
  • monocular field deficit
24
Q

What does damage to the L optic chiasm do?

A

Bitemporal meianopia

  • impaired peripheral vision bilaterall
  • affects nasal retina axons at decussations
25
Q

What does damage to the L optic tract do?

A

contrlateral homonomous hemianopnia

  • impaired visual field contrlateral to tract
  • R peripheral vision and left nasal vision
26
Q

What does damage to LGN axons around inferior horn do?

A

Superior portion of contrlateral homonomous

-1/4 field okay

27
Q

Why does macular sparing occur?

A

Redundant sampling of each quadrant
OR
MCA and ACA blood supply

28
Q

What is the pathways of the pupilary light reflexes?

A

Retinal ganglia cells down CNII bypass LGN-> Pretectal nucleus
Pretectal-> BILAT Ed-West nucleus
Ed West-> ciliary ganglia via CNIII )oculomotor)
Ciliary ganglia-> pupilary constrictor muscle

29
Q

Where is the CB of post-ganglionic nucleus in pupilary reflex?

A

ciliary gangliaa(along CNIII)

30
Q

Where are the CB of pre-ganglionic neurons in pupilary reflex?

A

Ed-westphal

31
Q

What is the area called where axons decussate from pretectub to contrlat E-W?

A

posterior commisure

32
Q

What is it called when the ipsilateral eye reflex contracts? Contralateral? Both at once?

A

Direct
Indirect
Consensual

33
Q

How would a lesion of the ipsilateral optic nerve affect pupilary reflex?

A

Direct and indirect Absent

34
Q

How would a lesion to the contralteral optic nerve affect pupilary reflex?

A

Direct and Indirect Present

35
Q

How would ipsilateral lesion to oculomotor nerve affect reflex?

A

Direct absent

Indirect present

36
Q

How would contrlateral lesion to oculomotor nerve affect reflex?

A

Direct present

indirect Absent

37
Q

What is the fusiform gyrus?

A

Occipotemporal gyri

  • source of facial representations
  • can get hallucinations if spontaneously activate
  • primary visual lesions can cause association areas like this to fire sporadically

Neuro Anatomy (8 decks)

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