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PNS > Unit 1 - C.N. II - Optic Nerve > Flashcards

Unit 1 - C.N. II - Optic Nerve Flashcards

1
Q

Outermost layer of the eye

A

Fibrous tunic

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2
Q

The fibrous tunic consists of what two things?

A

Sclera and cornea

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3
Q

What is the only part that goes completely around the eye?

A

sclera

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4
Q

What is the middle layer of the eye?

A

Vascular tunic

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5
Q

What are the three parts of the vascular tunic?

A

Ciliary body, Iris, choroid

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6
Q

Why is the vascular tunic not complete?

A

Because of the Iris - has a pupil

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7
Q

What is the innermost layer of the eye?

A

The retina

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8
Q

What layer is adjacent to the choroid?

A

Pigmented layer (cementing layer)

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9
Q

What is the next layer inward after the pigmented layer?

A

Photosensitive outer segments of rods and cones

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10
Q

What layer covers the rods and cones?

A

External limiting membrane

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11
Q

What layer contains the cell bodies of rods and cones?

A

Outer nuclear layer

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12
Q

Rods and cones synapse with bipolar cells here.

A

Outer Plexiform layer

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13
Q

Layer that contains the cell bodies of bipolar cells?

A

Inner nuclear layer

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14
Q

Layer where bipolar cells synapse with ganglion cells?

A

Inner plexiform layer

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15
Q

Layer of ganglion cell bodies?

A

Ganglion cell layer

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16
Q

Are retinal ganglion cell axons myelinated?

A

no

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17
Q

Layer containing the ganglion cell bodies?

A

Ganglion cell layer

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18
Q

Layer containing the retinal ganglion cell axons?

A

Nerve fiber layer

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19
Q

A glial boundary separating the retina from the vitreous body?

A

Internal limiting membrane

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20
Q

Name the layers from 1 -10 (choroid to vitreous body)

A 
Pigmented layer
Photosensitive outer segments of rods and cones
External limiting membrane
Outer nuclear layer
Outer plexiform layer
Inner nuclear layer
Inner plexiform layer
Ganglion cell layer
Nerve Fiber layer
Internal limiting membrane
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21
Q

What is the distal end of the photoreceptor called?

A

The outer segment

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22
Q

The outer segment of the photoreceptor is closes to what?

A

The choroid

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23
Q

The outer segment of the photoreceptor has two shapes. What are they?

A

Cylindrical (rod shaped) and tapered (cone shaped)

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24
Q

There are three types of cones that receive information, they are?

A

Red, green, and blue

25
Q

What is required for the cones to work?

A

Light

26
Q

Where are the cones more concentrated?

A

Toward center of the retina (fovea)

27
Q

What are the only thing rods sense?

A

Light and dark (only shades of grey)

28
Q

Are there rods in the fovea?

A

NO

29
Q

What is the periphery of the retina completely composed of?

A

rods

30
Q

When depolarized, photoreceptors relay information to bipolar cells by synapsing in what layer?

A

Outer plexiform layer

31
Q

Axons from ganglion cells are coveted in the nerve fiber layer toward the _____.

A

Optic disc

32
Q

Where does the optic nerve attach to the eye?

A

Optic disc

33
Q

Where are the axons from nerve fiber layer carried in outside of the eye?

A

In the optic nerve

34
Q

Are ganglionic cells myelinated?

A

no

35
Q

When do the axons of the ganglion cells become myelinated?

A

When they leave the eye

36
Q

The optic nerve enters the skull through the _____ and unites to form the ______.

A

Optic canal

Optic chiasma

37
Q

Are optic nerve fibers myelinated?

A

yes

38
Q

What cells form the myelination of the optic nerve?

A

(interfasicular) oligodendrocytes

39
Q

In the optic chiasma which fibers cross?

A

Fibers from the medial (nasal) side of the retina

40
Q

In the optic chiasma which fibers do not cross?

A

Fibers from the lateral (peripheral) side of the retina

41
Q

The optic tract travels around what?

A

Cerebral peduncles

42
Q

After traveling around the cerebral peduncles, the optic tract fibers synapse which three nuclei of termination?

A

Lateral geniculate body
Superior colliculus
pretectal nucleus of the midbrain

43
Q

The majority of optic tract fibers synapse in which N.O.T.?

A

Lateral geniculate body

44
Q

After synapsing in the lateral geniculate body, where is the information relayed?

A

The cerebral cortex in the occipital lobe (B.A. 17)

45
Q

After synapsing in the superior colliculus, where is the information relayed to?

A

The tectospinal tract

46
Q

What are the two muscles influenced by the tectospinal tract?

A

trapezius

sternocleidomastiod

47
Q

Fibers from rods/cones to SCM/trapezius arrive via what nerve?

A

C.N. XI - accessory nerve

48
Q

The tectospinal tract goes down to what level of the spine?

A

C4

49
Q

How many neurons are in the optic pathway?

A

3 - photoreceptor to bipolar to ganglionic

50
Q

Colorblindness is most common in _____?

A

males

51
Q

Most colorblindness is sex-linked on which chromosome?

A

X

52
Q

Optic nerve lesion causes?

A

Loss of depth perception, decrease in size of visual field (

53
Q

Decussating fibers of the optic chiasma causes?

A

tunnel vision, lose peripheral vision

54
Q

What passes through the optic chiasma that can lead to tunnel vision?

A

infundibular stalk, so a pituitary lesion can cause

55
Q

Lesion of the optic tract causes?

A

One side of vision is gone (opposite side of lesion)

56
Q

Which 3 visual reflexes test C.N. II - sensory/afferent only?

A

Direct and consensual reflexes
Accommodation reflex
Corneal reflex

57
Q

How do you test direct and consensual reflexes?

A

Shine light in L eye and swing light back and forth.
Direct = L pupil constricts
Consensual = R pupil slightly constricts

58
Q

What is the accommodation reflex?

A

Changing the shape of the lens to focus near and far

59
Q

How do you test convergence?

A

Use a pen and move pen towards patient’s nose. Eyes should coverage and track in.

PNS (15 decks)

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