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Anatomy > 10 - NS Eye & Vision > Flashcards

10 - NS Eye & Vision Flashcards

1
Q

What are the types of tunics of the eye

A
  1. fibrous tunic
  2. vascular tunic
  3. retina
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2
Q

which are fibrous tunics

A

sclera and cornea

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3
Q

which are vascular tunics

A

choroid, ciliary body and iris

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4
Q

what type of layers is the retina

A

pigmented and nervous

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5
Q

how does the retina work

A
  1. incident light passes through the neural layers of the retina to reach the photoreceptors
  2. the pigmented retina absorbs excess light
  3. interneurons preprocess sensory info
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6
Q

What are retinal ganglion cells

A

they form CN II (optic nerve)

receive signals from photoreceptors and retinal interneurons

RGC projections transmit signals via the optic nerve to the areas in the brain used for visual processing

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7
Q

What are the interneurons

A

amacrine cells
bipolar cells
horizantal cells

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8
Q

parts of the retina

A

macula
fovea

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9
Q

Macula

A

3-5 mm oval region w/in the central region of the retina

surrounds the fovea

our central vision, most of our colour vision and the fine detail of what we see

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10
Q

Fovea

A

central fixation point for each eye
highest visual acuity (eye focusing)
- avascular (so u don’t see vessels)

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11
Q

What is the tool used to view the retina and how does it work

A

ophthalmoscope
dilates the pupil

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12
Q

What is the optic disc

A

beginning of the optic nerve and is the point where the axons of retinal ganglion cells come together.
blind spot

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13
Q

What happens aar of high CSF presure in the retina

A

buldge

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14
Q

what happens aar of loss of RGC axons

A

cupping

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15
Q

what is hyperopia + what lens is used

A

farsightedness - hard to read books(60% of population)
- eyeball is flattened
- focal point is behind the eye

positive diopter lense

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16
Q

What is presbyopia + what lens is used

A

can’t focus on objects that are near, far is fine
in old people

positive diopter lens

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17
Q

what is Myopia + what lens is used

A

nearsightedness - 20-30% of the population
eyeball is elongated
- focal point is before

negative diopter lens

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18
Q

what is lens cataracts

A

vision loss
begins at the age of 40
may also affect the cornea
can be corrected with surgery
- looks like many focal point

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19
Q

which SENSORY cranial nerves are involved in vision

A

CN II (optic): light detection
CN V (trigeminal): cornea sensation

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20
Q

Which MOTOR cranial nerves are involved in vision

A

CN III (oculomotor)
CN IV (trochlear)
CN VI (abducens)
CN VII (facial): lacrimal secretions

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21
Q

What are the structures of the primary visual pathway

A

optic nerve (CN II)
optic chiasm
optic tract
lateral geniculate nucleus (LGN)
optic radiations
primary visual cortex

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22
Q

What happens at the optic chiasm

A

optic nerves come together in order to allow for the crossing of fibers
enables vision from one side of both the eyes to be appreciated by the occipital cortex of the opposite side

23
Q

Lateral geniculate nucleus

A

passes through the thalamus

24
Q

What are the visual field defects

A
  1. monocular blindness (loss of vision in one eye)
  2. bitemporal hemianopia (temparol visual fields are gone - peripheral gone)
  3. homonymous hemianopia (half visual field gone - can’t see one side)
25
Q

What causes glaucoma

A

increased intraocular pressure (excess production or insufficient drainage of aqueous humor)

26
Q

How is vision affected by glaucoma

A

vision loss b/c damage to reinal ganglion cells -> cupping in optic disc
progresses from the periphery to the center of the visual field

27
Q

what is aqueous humor

A

produced by the ciliary body and drained by the trabecular meshwork

28
Q

What are the motor nerves

A

3 -> occulomotor
4 -> trochlear
6 -> abducens
7 -> facial (lacrimal secretions)

29
Q

what does CN III do

A

occulomotor
levator palpebrae (opens eyelid)

30
Q

what does CN VII do

A

facial
orbicularis oculi (closing eyelid)
innervates lacrimal glands which secrete tears

31
Q

What is saccadic eye movements

A

expose the fovea of the retina to the entire visual scene
- involves engaging the extraocular muscles of the eye

32
Q

Where do extraocular eye muscles origniate

A

from the bones of the orbit and insert on the sclera of the eye
- medial (nasal) aspect of the orbit

33
Q

What are the rectus muscles

A

lateral, inferior, superior, medial
straight

pulls up and towards nose

34
Q

What are the oblique muscles

A

superior, inferior
angled

pulls down and out

35
Q

What nerve controls the lateral rectus

A

CN VI

36
Q

What nerve controls the superior rectus

A

CN III

37
Q

What nerve controls the medial rectus

A

CN III

38
Q

What nerve controls the superior oblique

A

CN IV

39
Q

Which muscles allow u to look up

A

CN III superior rectus and CN III inferior oblique

40
Q

Which muscles allows you to look down

A

CN III inferior rectus and CN IV superior oblique

41
Q

What is diplopia

A

double vision caused by problems with conjugate eye movements

42
Q

What are the types of diplopia

A

occulomotor palsy/paralysis (CN III) - cant open eyelid

trochelar palsy (CN IV) - can’t rotate eyes within orbit

Abducens palsy (CN VI) - cant not adbuct eye

43
Q

What is ptosis

A

dropping of the eyelid
- weakness of the levator palpebrae

44
Q

What is exotropia

A

‘down and out’ deviation of the eye
- decreased tone of all muscles except the lateral rectus (‘out’) and the superior oblique (‘downward’)

lesion with CN III occulomotor nerve

45
Q

What is esotropia

A

medial deviation of one or both eyes
- lack of muscle tone of the lateral rectus muscle

lesion with abducens (CN VI) nerve

46
Q

How does lateral gaze work

A

brainstem circuits help
- tying together r/l abducens nucleus with the opposite occulomotor nucleus to contract the l/f lateral rectus muscle and the l/r medial rectus muscle

47
Q

What is convergence and accommodation

A

external eye muscles and pupils work together to position the eyes and the lens to focus

48
Q

What happens when you change from far to near vision

A
  1. contraction of both medial rectus m. (CN III)
  2. contraction of ciliary body to focus lens
  3. constriction of pupil to increase depth of field
49
Q

what happens to the parts of the eyes when viewing a distant object

A

ciliary muscles relax, zonular fibers raunt and lens flattens = distant object

nearly parallel light rays

50
Q

What happens to parts of the eyes when viewing a close object

A

via accommodation

ciliary muscles contract, zonular fibers lloose, lens becomes more spherical

divergent light rays

51
Q

how are pupillary constrictions accomplished
What is it used for

A

through parasympathetic stimulation of the pupillary sphincter
(limits light coming in)
reduce light intensity and increase the depth of field for near vision

52
Q

how are pupillary dilations accomplished
What is it used for

A

through sympathetic stimulation of the radial muscles of the pupil
increases light intensity and increases light exposure to the parafoveal regions of the retina
useful to increase peripheral vision during a flight or fight response

53
Q

What is ptosis
which system causes this

A

dropping of eyelid
sympathetic nerve

Anatomy (18 decks)

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