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PT 631 Neuroanatomy > Special Senses - Vision > Flashcards

Special Senses - Vision Flashcards

1
Q

describe the transmission of light through the pathways

A
  • visual field stimulus (light/light patterns)
  • peripheral NS (eye)
  • CN for eye movement (3, 4, 6)
  • optic N
  • optic tract
  • lateral geniculate body of thalamus
  • primary visual cortex (17)
  • visual association area (18)
  • frontal eye fields (8)
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2
Q

what is the name of the pathway associated with light/vision

A

retinogeniculocalcarine pathway

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3
Q

what are the 3 functions of the visual system

A
  • sight for recognition and location of objects
  • provide information to be used in postural and limb control
  • eye movement control
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4
Q

what structures make up the peripheral visual system

A

the eyeball itself
- pupil, retina, iris, lens, cornea, ciliary body, vitreous humor, macula, sclera, choroid, retina

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5
Q

clear covering over the colored iris, major light focusing structure

A

cornea

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6
Q

whites of the eyes; filled with blood vessels

A

sclera

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7
Q

mucous membrane lining of the eyelid - houses blood vessels

A

conjunctiva

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8
Q

tear ducts, lacrimal gland keep eye clean and protect from disease

A

lacrimal system

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9
Q

colored part of the eye; divides internal space into anterior and posterior chambers

A

iris

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10
Q

perforation in center of iris; controls how much light comes in

A

pupil

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11
Q

what two muscles determine how much light comes into the eye by controlling the pupil

A

dilator and sphincter muscles

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12
Q

constricts pupil in bright ligth

A

sphincter muscle

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13
Q

dilates pupil in dark

A

dilator muscle

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14
Q

what innervates sphincter muscle

A

ANS branch of CN 3

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15
Q

what innervates dilator muscle

A

ANS branch of CN 5

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16
Q

deepest layer of the iris and accommodates for near/far vision

A

lens

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17
Q

immediately behind iris, contains blood vessels that produce aqueous humor

A

ciliary body

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18
Q

fills the anterior chamber to provide metabolic support for the lens and creates intraocular pressure

A

aqueous humor

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19
Q

if intraocular pressure becomes too high, what can it lead to

A

glaucoma –> damages the optic N

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20
Q

gel-like material in front of the retina; maintain shape of globe

A

vitreous humor

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21
Q

lens adopts different shapes in order to focus the light entering the eye via ciliary muscles

A

accomodation

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22
Q

center 1cm diameter of retina; degenerates with aging process decreasing visual acuity

A

macula

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23
Q

central 1.5 mm-diametr center of macula

A

fovea

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24
Q

what does the fovea only contain

A

cones

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25
Q

circular elevated region where optic N exits the eye

A

optic disk

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26
Q

has no rods or cones

A

blind spot in optic disk

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27
Q

the retina is a 10 layered peripheral receptor that is stimulated by what

A

photons (light energy)

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28
Q

what are the 3 major cells types in the retina and what do they do

A
  • rods: located in periphery of retina (scotopic - low level illumination, limited resolution, insensitive to color) –> dark
  • cones: located in center of each retina (photopic - high level illumination, sharp vision, sensitive to color bands of light via cone pigments (blue, green, red)
  • ganglion cells: second order neurons (output cells) that are axons that form optic N
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29
Q

sharp vision

A

vision acuity

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30
Q

what colors are cone pigments sensitive to

A

blue, green red

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31
Q

the retina converts light into neuronal signals via what

A

G-proteins

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32
Q

____ and _____ retinas from each eye become axons that merge together as they exit the back of the eye as the optic N

A

nasal and temporal retinas

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33
Q

what is the optic N made of

A

nasal (medial) and temporal (lateral) axons of ganglion cells (2nd order neurons) in retina that merge to form a bundle of 1 million fibers as it pierces the back of the eye

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34
Q

is the optic N CNS or PNS

A

CNS - myelinated by oligodendrocytes

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35
Q

what does the optic N travel through and where does it cross

A
  • optical canal
  • optic chiasm
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36
Q

what does the optic N become after crossing at chiasm

A

optic tract

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37
Q

where does the optic tract synapse

A

lateral geniculate body of thalamus (3rd order neurons)

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38
Q

after synapsing in thalamus, where does information go

A

primary visual cortex (17)

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39
Q

portion of space that can be viewed by the retina when the eye is fixated straight ahead without eye/head movement

A

visual field

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40
Q

which retina (nasal or temporal) crosses at optic chiasm

A

nasal

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41
Q

are optic N and optic tracts PNS or CNS

A

CNS

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42
Q

from the lateral geniculate nucleus to occipital lobe

A

calcarine pathway

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43
Q

he overlapping of the central portion of the visual fields from each eye create a superimposed single impage

A

binocular vision

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44
Q

where is R visual field information sent to

A

L occipital lobe

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45
Q

what info is carried on nasal retinas

A

carry ipsilateral temporal field info

46
Q

what info is carried on temporal retinas

A

contralateral nasal field info

47
Q

what do optic tracts carry

A

contralateral nasal and temporal fiber information

48
Q

what does damage to the optic N cause

A

loss of vision in one whole eye

49
Q

what does damage to optic chiasm lead to

A

bitemporal heminopsia

50
Q

what does damage to optic tract lead to

A

homonymous heminopsia (see, no see, see, no see)

51
Q

describe R visual field

A
  • L half or R retina (nasal)
  • L half of L retina (temporal)
52
Q

laminar arrangement of lateral geniculate body of thalamus

A
  • magnocellular layer: large neurons in layers 1 and 2 that receive information from type M ganglion cells in retina
  • paravocellular layer: small neurons in layers 3-6 that receive info from type P ganglion cells
53
Q

what laminar layers of lateral geniculate receive info from contralateral eye

A

1, 4, 6

54
Q

what laminar layers of lateral geniculate receive info from ipsilateral eye

A

2, 3, 5

55
Q

is made up of projection fibers carrying information from the superior visual fields and terminate on primary visual cortex below calcarine sulcus

A

Meyer’s loop

56
Q

information from the inferior visual fields terminates on the primary visual cortex ____ the calcarine sulcus

A

above

57
Q

______ injuries will result in visual field deficits due to path of Meyer’s loop around 4th ventricle

A

temporal lobe

58
Q

what lobes are visual cortices found

A

occipital lobe

59
Q

area 17 and other name

A

primary visual cortex
striate cortex I

60
Q

where is visual acuity located in primary visual cortex

A

most posterior and over greatest area of cortex

61
Q

where is peripheral vision located in primary visual cortex

A

rostrally - assures accurate foveal vision for survival

62
Q

what does primary visual cortex do

A

distinguishes intensity of light vs dark (not color), shape, size, location and movement of objects

63
Q

visual association area numbers

A

18-21

64
Q

what does visual association area do

A

analyzes colors and motion, fixation of objects in central vision; gives meaning to visual information

65
Q

what can occur if damage to visual association area

A

visual agnosia –> cannot recognize or associate significance of what is seen; loss of eye coordination and loss of visually guided hand activities

66
Q

involved in circadian rhythms of day-night cycle

A

suprachiasmic nucleus of hypothalamus

67
Q

connects eyes and ears –> turning to look at a sound

A

superior colliculus of midbrain

68
Q

reflexive responses of pupils; orientation of the eyes and head in coordination with auditory stimuli (coordination with tectospinal tract); projects information to posterior parietal cortex and visual association areas

A

pretectal area of midbrain

69
Q

coordination of eye movement requires synthesis of information from

A
  • head movements (vestibular)
  • visual objects (vision)
  • eye movement and position (proprioception)
  • selection of visual target (brainstem and cortex)
70
Q

eye remains abducted and down due to weakness in med/inf oblqiue; eyelid droop (ptosis) due to weakness of levator palpebrae superioris; pupil remains dilated; diploplia

A

CN 3 palsy

71
Q

eye add but elevates due to weakness in superior oblique; will have difficulty going downstairs and reading; diploplia

A

CN 4 palsy

72
Q

eye does not abd due to lateral rectus weakness, diploplia

A

CN 6 palsy

73
Q

what are the 2 objectives of eye movement

A
  • keep eyes stable head movement so environment doesn’t bounce (gaze stabilization or visual fixation) –> VOR and optokinetic nystagmus
  • directing gaze at visual targets
74
Q

normal response when things are moving around you, making you think you are moving when you aren’t

A

optokinetic nystagmus

75
Q

MLF is a bundle of axons connecting vestibular nuclei in the brainstem and cerebellum with

A
  • CN nuclei 3, 4, 6
  • CN nuclei 11
  • superior colliculus
76
Q

what CN are CNS

A

optic and olfactory

77
Q

both eyes move in the same direction

A

conjugate vision

78
Q

fast eye movement to switch gaze from one object to another (eyes switch from person entering room while reading a book)

A

saccades

79
Q

what regulates saccades

A

superior colliclus

80
Q

eye movement follows a moving object like a person walking down sidewalk

A

smooth pursuit

81
Q

eyes move either toward or away from midliine together (near to far vision); Involves cilliary muscles, medial recti and pupillary constriction to increase the curvature and refractive power of the lens

A

accomodation-convergence reflex

82
Q

eyes move away from midlien

A

accomodation

83
Q

eyes move toward midline

A

convergence

84
Q

what is the normal distance before image doubles/blurs as it moves toward tip of nose

A

8-10 inches

85
Q

what two reflexes stabilize gaze

A
  • vestibulo-ocular reflex (VOR)
  • optokinetic reflex
86
Q
  • stabilizes visual images during movement of the head
  • elicited by head rotation, flexion or extension
    Info from semicircular canal → vestibular nuclei → CN 3 and 6
  • results in movement of eyes opposite direction of head movement
A

Vestibulo-occular reflex

87
Q
  • adjusts eye position during slow head movement
  • elicited by moving the stimulus
  • allows eyes to follow the objects in the visual field - eyes move from edge of visual field followed by a saccade
  • influences perception of movement - stopped car with moving bus next to it
A

optokinetic reflex

88
Q

physiological/normal nystagmus

A
  • Normal VOR reflexive response at end range positions of the eyes
  • Quick saccadic movement back to midline
  • Can elicit by quick rotation of the head, temp stimulation of the inner ear or optokinetic stimulation
89
Q

pathological nystagmus can be caused by

A

CN VIII injury, injury to the vestibular apparatus in the inner ear, CNS lesions to the cerebellum or vestibular nuclei in brainstem

90
Q

mediates the size of the pupil to adjust amount of light projected to the retina

A

pupillary light reflex

91
Q

what structures are needed for pupillary light reflex

A
  • ganglia cells of retina
  • CN 2 and 3
  • pretectal region in midbrain
  • edinger-westphal nucleus
  • cilliary ganglia
  • sphincter muscles of the eye
92
Q

what type of response is pupillary reflex

A

parasympathetic

93
Q

cortical blindness occurs due to lesion where

A
  • prechiasmic retina or optic N
  • primary visual cortex due to thrombus or embolus in PCA, TBI, MS or anoxic pre/perinatal event
94
Q

has no awareness of visual info; may have blind spot; can perceive light and dark if retina is intact; eye can still move through full ROM; pupillary light reflex remains intact

A

cortical blindness

95
Q

damage to center of optic chiasm to nasal half of each retina; loss of info from both temporal field (no peripheral vision)

A

bitemporal hemianopsia/heteronymous hemianopsia

96
Q

what is common cause of bitemporal hemianopsia

A

pituitary adenoma

97
Q

lesion in pathway after the chiasm in optic tract, optic radiations or primary visual cortex; results in 1/2 of each visual field; if deficits is incomplete will only have 1/4 loss of visual field; may have macular sparing

A

homonymous hemianopsia

98
Q

double vision

A

diplopia

99
Q

inability to maintain stable vision when head is moving

A

gaze palsy

100
Q

involuntary oscillating movement of the eyes

A

nystagmus

101
Q

swelling of papilla of the retina as a result of increased ICP

A

papilledema

102
Q

inability to attach meaning to what is seen
- Damage to occipital lobe

A

visual agnosia

103
Q

inability to discriminate hue - not color blindness - a type of agnosia

A

achromatopsia

104
Q

inability to recognize a familiar face

A

prospagnosia

105
Q

inflammatory disorder - may lead to deymyelination often associated with MS

A

optic neuritis

106
Q

papilledma - what is, what does it indicate, caused by

A
  • optic disc swelling
  • elevated ICP
  • TBI, stroke, epidural/subdural hemorrhage
  • enlargement of blindspot
  • detected with opthalmoscope
107
Q

ptosis is the drooping of the eyelid due to poor innervation to what muscle and by what CN

A
  • levator palpebrae superioris
  • CN 3
108
Q

shrinking of visual field from the periphery due to build up of aqueous humor that increased the fluid pressure inside the eye

A

glaucoma

109
Q

what can glaucoma lead to

A

damage the retina, damage optic N and lead to blindness

110
Q

loss of transparency of the lens and can easily be repaired surgically

A

cataracts

111
Q

causes of cataracts

A

Genetic, exposure to UV light, infrared or microwave radiation, secondary to diseases like DM, eye injury or trauma

112
Q
  • disease of the retina that damages the central region (fovea) where vision is the sharpest
  • loss of detail vision, face recognition, and reading
A

macular degeneration

PT 631 Neuroanatomy (17 decks)

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