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Neuro Exam 1 > Vision > Flashcards

Vision Flashcards

1
Q

2 essential functions of the eye

A

1) focus light on the retina (accomplished by concerted efforts of the cornea + lens)
2) transduction of light energy into action potentials (accomplished by the retina)

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2
Q

anterior chamber of the eye

A

space between cornea and iris

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3
Q

posterior chamber of the eye

A

space between the zonule fibers (lens) and the back of the iris

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4
Q

vitreal cavity of the eye

A

large space behind the lens, occupies by the vitreous body

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5
Q

sclera of the eye

A

fibrous cover of eye (white of the eye)

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6
Q

cornea of the eye

A

window into eye; clear covering; main refractive elements

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7
Q

iris of the eye

A

forms pupil

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8
Q

aqueous humor of the eye

A

*blood-derived, acellular fluid
*pressurizes the eye + maintains eye shape
*produced by CILIARY BODY
*flows from posterior chamber to anterior chamber

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9
Q

zonule fibers of the eye

A

ligaments that suspend the lens

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10
Q

ciliary body of the eye

A

consists of ciliary processes and ciliary muscle

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11
Q

ciliary muscles of the eye

A

control the shape of the lens

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12
Q

choroid of the eye

A

blood supply plexus serving outer retina, ciliary body, and iris

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13
Q

fovea of the eye

A

*area near central retina with a high concentration of photoreceptors (CONES ONLY)
*foveal pit: unobstructed light path

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14
Q

optic nerve of the eye

A

axons of retinal ganglion cells exiting the retina

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15
Q

blood supply of the eye

A

*provided by 2 branches of the ophthalmic artery:
1. central retinal artery
2. long and short posterior ciliary arteries

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16
Q

central retinal artery

A

*supplies blood to the inner retina
*enters via the optic nerve
*branch of ophthalmic artery

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17
Q

long and short posterior ciliary arteries

A

*form the choroid plexus between the sclera and the retinal pigment epithelium
*supplies blood to the outer retina, ciliary body, and iris
*branch of ophthalmic artery

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18
Q

how does the lens get nutrients

A

aqueous humor

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19
Q

how does the cornea get nutrients

A

relies on the tear film for oxygen, nutrients, and disposal of metabolic wastes

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20
Q

why are the lens and cornea not innervated by blood supply

A

maximizes image clarity

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21
Q

emmetropia

A

normal vision, in which light is focused at the level of the retina

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22
Q

hypermetropia / hyperopia

A

*far-sightedness
*when light is focused BEHIND the retina due to abnormal eye shape (too short) or not enough refractive power

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23
Q

correction for hypermetropia / hyperopia

A

convex lens

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23
Q

myopia

A

*nearsightedness
*when light is focused IN FRONT OF retina, due to abnormal eye shape (too long) or too much refractive power by cornea and lens

24
Q

correction for myopia

A

concave lens

25
Q

2 functions of cornea

A

1) refraction
2) protection

26
Q

refractive function of the cornea

A

*curvature of cornea accounts for majority of refractive power
*layers are optimized for transparency
*avascular to prevent blood vessels from obstructing the primary light path

27
Q

protective function of the cornea

A

*tight junctions in the epithelial layer form a barrier that is impermeable to chemicals and other potentially damaging agents
*highly innervated (mostly nociceptive) by CN V1

28
Q

function of the lens

A

*refraction for accommodation:
-fine focus mechanism
-refractive power depends on shape (spherical = higher power = near objects; flattened = lower power = far objects)

29
Q

what happens in the eye when the lens is not accommodated

A

*ciliary muscles are RELAXED
*zonule fibers are taught
*lens is FLATTENED

30
Q

what happens in the eye when the lens is accommodated

A

*ciliary muscles are CONTRACTED, causing the muscle to bulge out
*zonule fibers slack
*lens is SPHERICAL

30
Q

presbyopia

A

loss of ability to accommodate as we age

31
Q

accommodation innervation

A

1) Edinger-Westphal nucleus (preganglionic parasympathetics)
2) ciliary ganglion -> short ciliary nerves
3) ciliary muscle and pupillary constrictor

32
Q

what produces the aqueous humor

A

ciliary body

33
Q

what is path of flow of aqueous humor

A

*flows from point of origin in posterior chamber -> anterior chamber
*exits the eye to join the venous circulation of the sclera by way of the trabecular network and the Canal of Schlemm

34
Q

glaucoma

A

*usually occurs when the aqueous humor cannot drain, causing increased intraocular pressure and putting pressure on the optic nerve head, leading to degeneration of the nerve
*impairment of PERIPHERAL vision

35
Q

9 layers of the retina

A
  1. retinal pigment epithelium
  2. photoreceptor outer segment
  3. photoreceptor inner segment
  4. outer nuclear
  5. outer plexiform
  6. inner nuclear
  7. inner plexiform
  8. ganglion cell
  9. nerve fiber
36
Q

retinal pigment epithelium (layer of the retina)

A

*forms the blood-retinal barrier
*provides metabolic support of outer retina

37
Q

photoreceptor outer segment (layer of the retina)

A

*contains light-sensitive elements (rods and cones)

38
Q

photoreceptor inner segment (layer of the retina)

A

synthetic machinery of the photoreceptors

39
Q

outer nuclear (layer of the retina)

A

photoreceptor cell bodies

40
Q

outer plexiform (layer of the retina)

A

a layer of synapses between photoreceptors and intraretinal relay neurons

41
Q

inner nuclear (layer of the retina)

A

cell bodies of relay neurons

42
Q

inner plexiform (layer of the retina)

A

synapses of relay neurons to ganglion cells

43
Q

ganglion cell (layer of the retina)

A

cell bodies of the ganglion cells

44
Q

nerve fiber (layer of the retina)

A

axons of the ganglion cells, which come together at the optic nerve head to exit the eye as the optic nerve (CN II)

45
Q

cones

A

photoreceptors specialized for vision in bright light (specialized for COLOR)

46
Q

rods

A

photoreceptors specialized for dim-light vision

47
Q

macular degeneration

A

affects the fovea (impairment of CENTRAL vision)

48
Q

ascending visual pathway (from retina to primary visual cortex)

A

1) axons of the retinal ganglion cells exit the retina and form the optic nerve
2) optic nerve partially decussates in the optic chiasm to form the optic tract
3) axons synapse in the LGN of the thalamus
4) from LGN, axons project to the primary visual cortex (above and below the calcarine fissure)

49
Q

visual cortex on the right side of the brain represents what visual space?

A

LEFT half of visual space

50
Q

axons in the nasal retina…

A

*receive light from IPSILATERAL visual space
*cross in optic chiasm
*reach the CONTRALATERAL LGN

51
Q

axons in the temporal retina

A

*receive light from CONTRALATERAL space
*do NOT cross
*project to the LGN on the same side

52
Q

retinotopic map of visual cortex

A

*superior visual space (inferior retina) is mapped below the calcarine fissure
*inferior visual space (superior retina) is mapped above the calcarine fissure
*central visual space is represented most posteriorly
*peripheral visual space is represented more anteriorly
*central vision is represented in a disproportionately large amount of cortical tissue

53
Q

monocular visual loss

A

lesion of an optic nerve causes no sight from that eye

54
Q

bitemporal hemianopia

A

*lesion of the optic chiasm
*affects the nasal retina of both eyes, causing loss of both temporal visual fields
*a pituitary tumor could cause this

55
Q

macular sparing

A

vision is spared in the parafoveal region due to the amount of neural tissue devoted to central visual space (because lesions are rarely extensive enough to obliterate the magnified cortical representation of central vision)

56
Q

contralateral homonymous hemianopia

A

*one half of visual space (example, left temporal and right nasal) vision is lost
*can be caused by lesion of optic tract, optic radiation (fibers from LGN to visual cortex), or primary visual cortex (upper and lower)

Neuro Exam 1 (22 decks)

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