Visual System Part II And III Flashcards

1
Q

What are the first order neurons of the optic pathway

A

Ganglion cells that travel in the optic nerve into the optic chiasm

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2
Q

What do axons coming from the lateral retina do at the optic chiasm

A

Do not decussate, they enter the ipsilateral optic tract

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3
Q

What do the axons that come from the medial retina do at the level of the chiasm

A

Decussate and enters the contralteral optic tract

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4
Q

Where do fibers from each optic tract terminate

A

In the lateral geniculate nucleus

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5
Q

What are the second order neurons in the optic pathways

A

Geniculate fibers

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6
Q

Where do the geniculate fibers travel

A

Through the internal capsule and corona radiata to the primary visual cortex in the banks of the calcarine sulcus

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7
Q

What is the extra geniculate pathways

A

Sensory fibers for pupil/EOM movements

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8
Q

Where do the extra geniculate fibers enter

A

They bypass the LGN and enter the pretectal area and the superior colliculus

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9
Q

What is the pretectal area important for

A

Pupillary light reflex

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10
Q

What is the superior colliculus and the pretectal area involved with

A

Directing eyes toward visual stimuli

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11
Q

Is the extra geniculate pathway involved with vision

A

No

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12
Q

Fibers arising from the lateral geniculate nucleus curve around the lateral wall of the lateral ventricular as the _________

A

Optic radiation

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13
Q

Where do the optic radiations terminate

A

In the cortex adjacent to the calcarine sulcus

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14
Q

What part of the visual field does the upper retina represent

A

Lower

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15
Q

Where does the upper retina projector in the calcarine sulcus

A

Above the calcarine sulcus

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16
Q

What part of the VF does the lower retina represent

A

Upper VF

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17
Q

What part of the calcarine sulcus does the lower retina project to

A

Below the calcarine sulcus

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18
Q

How do projections from the upper retina course in the optic radiations

A

Upwards in parietal lobe, around lateral ventricle to visual cortex above calcarine

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19
Q

How do the lower retina optic radiations course back

A

Downwards through temporal lobe towards calcarine sulcus

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20
Q

Where do the macular fibers project

A

In a broad region, some go with the superior optic radiations, some with the inferior optic radiations

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21
Q

Lesions affecting the optic radiation and the macula

A

Often cause visual loss in one quadrant of the vision field with macular sparing

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22
Q

Superior retina projects

A

To the cortex above the calcarine sulcus

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23
Q

Inferior retina projects to the

A

Cortex below the calcarine sulcus

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24
Q

Where is the macula represented

A

More posteriorly and peripheral fields than anteriorly. Represents a large area of the primary visual cortex

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25
Q

Representation of the macula compared to its size

A

Disproportionately large

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26
Q

What is the blood supply of the optic radiations

A

MCA

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27
Q

What is the blood supply for the superior branch of the optic radiation

A

Superior branch of MCA

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28
Q

What is the blood supply of the inferior optic radiations

A

Inferior branch of the MCA

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29
Q

What is the blood supply to the visual cortex

A

PCA

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30
Q

How are visual named

A

According to the VF loss and NOT ACCORDING TO THE AREA OF THE RETINA OR THE OPTIC PATHWAY THAT IS NONFUNCTIONAL

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31
Q

Loss of the whole VF in one or both eyes

A

Blindness

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32
Q

Loss of half of a VF

A

Hemianopia

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33
Q

Loss of one quarter of a VF

A

Quadrantanopia

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34
Q

Same field loss in both eyes

A

Homonymous

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35
Q

Opposite field loss in both eyes

A

Heteronimous

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36
Q

What is often used instead of heteronimous lateral hemianopia?

A

Bitemporal hemianopia

37
Q

What is often used instead of left or right homonymous hemianopia

A

Left or right hemianopia

38
Q

Is the lesion is before the chiasm

A

One eye is affected

39
Q

If the lesion is after the chiasm

A

Both eyes are affected

40
Q

Optic nerve damage

A

Ipsilateral blindness (right ON damage, right blindness)

41
Q

Damage to the optic chiasm in the middle

A

Bitemporal hemianopia

VF loss in each eye temporally

42
Q

Damage to the right optic chiasm from the side more temporally

A

Left hemianopia in the right eye

43
Q

Damage to the right optic tract

A

Left homonymous hemianopia

Same as if we lose the geniculate nucleus

44
Q

What is a common causes of damage to the optic chiasm

A

Pituitary tumor

45
Q

What is a common thing to damage the optic nerve

A

Embolism

46
Q

Ischemia or infarct in the temporal lobe (MCA) at the Meyers loop on the inferior optic radiation

A

Left superior quadrantanopia

Pie in the sky

47
Q

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

Right past the Meyers loop that affects both inferior and superior optic radiations

A

Left homonymous hemianopia

48
Q

Ischemia or infarct in the parietal or occipital lobe (MCA or PCA, affects superior optic radiation) kinda close to the visual cortex

A

Left inferior quadrantanopia

49
Q

Ischemia or infarct in the temporal or occipital lobe (MCA or PCA, affects inferior loops) kinda close to the visual cortex

A

Left superior quadrantanopia

50
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
51
Q

What radiation would need to be affected to get lower quadrantanopia

A

Superior

52
Q

What radatiation would be affected if you have upper quadrantanopia

A

Inferior

53
Q

Why do we get macular sparing if there is ischemia or infarct affecting occipital lobe that is supplied by the PCA?

A

Because the region of the occipital lobe where the macula is represented is ‘saved’ by collaterals coming from the MCA territory

54
Q

What do we “see” with

A

Our brains

55
Q

How does the brain perceive things

A

We detect motion, light and dark, and color and the abstracted properties are somehow reassembled into a unified perception.

56
Q

Our visual system can recognize objects independent of what

A

Angle or view, distance, and illumination

57
Q

Most input to primary visual cortex arrives at what cortical layer

A

4

58
Q

What is cortical layer 4 subdivided into

A

4A, 4B, 4Ca, 4b

59
Q

What cortical layer in 4 contains numerous myelinated axon collateral resulting in the pale- appearing stria of gennari that is visible with the naked eye?

A

Layer 4B

60
Q

Because of the distinctive stria from cortex layer 4B, what is the primary visual cortex also referred to as

A

Striate cortex

61
Q

Visual association cortex

A

From the primary visual cortex, neurons project to this area and other regions of the parietal-occipital and occipitotemporal cortex.

62
Q

What are the two main streams of higher order visual processing that are demonstrated in animals and humans

A
  • dorsal pathways that project to the parietal-occipital association cortex (Where?)
  • ventral pathways that project to the occipitotemporal association cortex (What?)
63
Q

What do the dorsal pathways of the visual association cortex do

A

Anywhere the question ‘where?’ by analyzing motion and spatial relationships between objects as well as between the body and visual stimuli

64
Q

What does the ventral pathway of the visual association cortex do

A

Answers the question “what?” by analyzing form, with specific regions identifying colors, faces, letters, and other visual stimuli

65
Q

Where is the separation of the dorsal and ventral pathways of the visual association cortex?

A

At the level of the retina

66
Q

Channels for analyzing motion, form, and color

A

All sent through different parallel channels that go to different layers of the primary visual cortex

67
Q

What is the condition where patients are unable to recognize people by looking at their faces

A

Prosopagnosia

68
Q

What type of lesion is responsible for prospagnosia

A

Bilateral inferior occipitotemporal cortex, also known as the fusiform gyrus

69
Q

Which hemisphere is mroe important for face recognition?

A

Some say the right one is, but in most reported cases, lesions are bilateral

70
Q

People with prosopagnosia cannot recognize people by their face, but they can identify people by what

A

Their clothes, voices, or other cues

71
Q

Awareness of the left hemisphere

A

Is aware of the right part of the world

72
Q

Right hemisphere awareness

A

Aware of both with only slight dominance to the left

73
Q

The VFs in someone with hemineglect syndrome

A

Intact

74
Q

What does the damage affect in hemineglect syndrome

A

Right hemisphere

75
Q

What is there an inability of in he I neglect syndrome

A

To pay attention to or notice stimuli from one half of the VF

76
Q

Where does the loss occur in someone with meineglect syndrome

A

Occurs on the left side of the VF as the result of right parietal damage

77
Q

What are some weird things that people with me I neglect syndrome do

A

Perceive only the right half of an object, if asked to copy an image, they will only draw the right half. They will eat food from only half of their plate

78
Q

Results in decreases or absent vision in an eye that otherwise is normal

A

Amblyopia

79
Q

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

A

Amblyopia

80
Q

Where is the cause of amblyopia

A

Within the brain

81
Q

What increases the chance of successful treatment in children with amblyopia

A

Detecting strabismus in early childhood

82
Q

Most common cause of amblyopia

A

Strabismic amblyopia

83
Q

What are the types of amblyopia

A

Strabismic
Refractive (differing refractive error)
Deprivation (congenital cataract)

84
Q

What is a symptom give away for someone with an embolism

A

Sudden visual loss in one eye

85
Q

What is a symptom give away for RD

A

A veil falling or black curtain

86
Q

What is a symptom giveaway for someone floaters

A

Dust particle, lint, moving black spots

87
Q

What is a symptom give away for someone with acute angle closure glaucoma

A

Pain and redness

88
Q

What is a symptom giveaway for viral conjunctivitis

A

Redness with WATERY discharge

89
Q

What is a symptom give away for bacterial conjunctivitis

A

Redness with PURULENT discharge