Visual Tracts Flashcards

1
Q

What are the 3 layers/tunics of the eye from superficial to deep?

A

Fibrous layer
Vascular layer
Retina

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2
Q

What is included in the Fibrous layer of the eye?

A

Sclera and cornea

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3
Q

What is included in the Vascular layer of the eye?

A

Choroid, ciliary body, iris

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4
Q

What is included in the Retinal layer of the eye?

A

Retina

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5
Q

Function of the sclera?

A

External layer of dense regular CT that protects internal structures and is an attachment site for the extraocular muscles

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6
Q

How many layers does the cornea have?

A

5

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7
Q

What are the layers of the cornea from superficial to deep?

A
Corneal epithelium
Bowmen's (anterior limiting) membrane
Stroma
Descemet's (posterior limiting) membrane
Inner endothelium
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8
Q

What type of tissue is the most superficial layer of the cornea?

A

The corneal epithelium is made of nonkeratinized stratified squamous

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9
Q

What cell type is in the 3rd layer of the cornea?

A

The stroma consists of keratocytes

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10
Q

What is the thickest layer in the cornea?

A

The stroma (3rd layer)

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11
Q

Where is the limbus?

A

It encircles the entire cornea and is the site where the cornea and sclera merge together

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12
Q

What is the purpose of the limbus?

A

It creates the conjunctiva that lines the anterior sclera and contains epithelial stem cells that will give rise to progenitor cells that move into the cornea

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13
Q

Qualities of the choroid in the vascular layer of the eye?

A

Contains many melanocytes and absorbs scattered light, prevents light from entering other places besides the pupil

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14
Q

2 main layers of the retina?

A

Pigmented Epithelium and the inner neural layer

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15
Q

What type of cells are the outer Pigmented Epithelium of the retina?

A

Simple cuboidal

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16
Q

What does the inner neural layer of the retina become once it moves anteriorly?

A

Ora serrata

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17
Q

What are the layers of the inner neural layer of the retina from first to receive light to last?

A
Inner limiting membrane (ILM)
Nerve fiber layer (NFL)
Ganglionic layer (GL)
Inner plexiform layer (IPL)
Inner nuclear layer (INL)
Outer plexiform layer (OPL)
Outer nuclear layer (ONL)
Outer limiting membrane (OLM)
Rods and cone layer 
Pigmented layer (PL)
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18
Q

Once light travels to the rod and cone layer of the retina (9), then what happens?

A

The signal propagates back the way it came to find the nerve fiber layer (2) that contains the ganglionic cell axons that will form CN2 - optic nerve

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19
Q

Area in the retina with the highest concentration of cones and the highest visual acuity?

A

Fovea

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20
Q

Area surrounding the fovea that protects the cones?

A

Macula lutea

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21
Q

Where do ganglion axons converge and what is missing there?

A

Optic disc, no photoreceptors = blind spot

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22
Q

What forms the optic nerve?

A

Axons of retinal ganglion cells that become myelinated as they pass through the sclera going towards the brain

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23
Q

What is a visual field?

A

Area that a person is able to see

24
Q

Central region of the visual field that is seen by both eyes

A

Binocular zone

25
Q

One region for the right eye and one for the left = 2

Visual field seen only by the corresponding eye

A

Monocular zones

26
Q

What is a retinal field?

A

Location on the retina that an object in visual field is projected to

27
Q

How are visual fields divided into retinal hemifields?

A

Nasal and temporal hemifields and then upper and lower quadrants

28
Q

How are lesions in the visual pathway describe?

A

Their visual field deficits

29
Q

How is the image formed on the retina different than the image we see?

A

The image is inverted and flipped laterally

30
Q

The left visual field projects to?

A

Right side of retina and right side of brain

31
Q

What does the optic tract contain?

A

Ipsilateral temporal field and contralateral nasal field

32
Q

Where do the optic tracts terminate?

A

Lateral geniculate nucleus of the thalamus

33
Q

Outgoing fibers from the LGN are called?

A

Optic radiations

34
Q

The top part of the visual field projects?

A

To the bottom part of the retina

35
Q

The bottom part of the visual field projects?

A

To the top part of the retina

36
Q

The bottom part of the retina containing the upper hemifield projects to the LGN and then to where?

A

Lingual gyrus - inferior to the calcarine sulcus

37
Q

The upper hemifield fibers have to travel around the lateral ventricle, through the temporal lobe. What is created?

A

Meyer’s loop

38
Q

Damage to meyer’s loop?

A

Upper visual field deficits

39
Q

The top part of the retina containing the lower hemifield projects to the LGN and then to where?

A

Cuneus - superior to the calcarine sulcus

40
Q

Where do fibers from the macula and fovea target in the visual cortex?

A

Most posteriorly - occipital pole

41
Q

What consumes disproportionately large volumes of the LGN and visual cortex compared to its size?

A

Fovea and macula

42
Q

Important in directing eye movements

A

Superior colliculus

43
Q

Important in pupillary light reflex

A

Pretectal area

44
Q

Besides the visual cortex, the LGN sends targets where?

A

Parieto-occpital-temportal area = visual association area for interpretation

45
Q

Blindness in 1 half of visual field

A

Hemianopia

46
Q

Blindness in quadrant of visual field

A

Quadrantanopia

47
Q

Visual field losses are similar in both eyes

A

Homonymous visual field

48
Q

2 eyes have non-overlapping field losses

A

Heteronymous visual field

49
Q

Visual field loss that preserves vision in center of visual field

A

Macular sparing

50
Q

When deficit of visual field from 1 eye can be superimposed on to the other eye (symmetrical)

A

Congruous

51
Q

Where are deficits most likely to be congruous?

A

Closer to the visual cortex

52
Q

Damage anterior to chiasm

A

Affects ipsilateral eye

53
Q

Damage at chiasm

A

Heteronymous deficits

54
Q

Damage behind chiasm

A

Homonymous deficits

55
Q

Associate visual agnosia

A

Pt cannot name or describe object but can recognize and demonstrate its use
Disconnects the language area from visual association area

56
Q

What may cause associate visual agnosia?

A

Infarction of LEFT occipital lobe and posterior corpus callosum