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Neuroscience > Visual System > Flashcards

Visual System Flashcards

1
Q

horizontal gaze (right) steps

A

L cortex FEF activated
R pontine gaze center @ paramedian pontine reticular formation (PPRF)
R abducens nuc (synapse on 2 things)
1. abducens (VI) contract R lateral rectus muscle
2a. cross midline, along medial longitudinal fasciculus to oculomotor nuc in midbrain
2b. occulomotor (III) contract L medial rectus muscle

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2
Q

lesion to abducens nerve

A

stop ipsilateral abduction

R lesion, R eye can’t abduct

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3
Q

lesion to abducens nucleus

A

bilateral inability to look towards lesion (abduct ipsi, adduct contra)

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4
Q

lesion to PPRF

A

bilateral inability to look towards lesion (abduct ipsi, adduct contra)

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5
Q

abducens nuc lesion complications

A

may have ipsi facial paralysis (VII loops around nuc)

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6
Q

lesion MLF

A

internuclear opthalmoplegia
contra eye cannot adduct (for conjugate)
convergence in tact (EdWest still ok)
ipsi eye has nystagmus

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7
Q

differentiate MLF vs III lesion

A

cannot adduct but can elevate –> III in tact

convergence is intact –> III in tact

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8
Q

lesion cerebral cortex (primary visual - FEF)

A

neither can look to contra side (R lesion, can’t look L)

slow drift to ipsi side (R lesion, drift R)

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9
Q

complications of primary visual cortex lesion

A

FEF close to RUL motor cortex

may have RUL weakness

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10
Q

aqueous humor path

A 
secreted by ciliary bodies into post chamber
go thru pupil 
circulate in ant chamber
taken up by canal of schlemm
go to venous system
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11
Q

glaucoma mech

A

problem draining aqueous humor –> intraoccular P builds up –> optic disc cupping - affect longest nerves first (lose peripheral vision)

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12
Q

light reflex (constriction) steps

A
  1. light stim optic nerve
  2. optic n stim pretectum (in midbrain)
  3. stim both EdWest nucs
  4. both pregang para III synapse in ciliary ganglia
  5. both postgang para stim pupillary constrictor muscle
  6. pupil constricts (miosis)
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13
Q

neurosyphilis and light reflex

A

affect pretectum
stop pupillary light reflex bilaterally
near response in tact
(Argyll Robertson pupil)

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14
Q

pineal tumor and light reflex

A

compress pretectum
stop pupillary light reflex bilaterally
near response in tact
(Argyll Robertson pupil)

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15
Q

light reflex (dilation) steps

A 
hypothalamus
DHF
T1
superior cervical gang
pupillary dilator muscle
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16
Q

events of near response

A

accommodation
convergence
pupillary constriction

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17
Q

accommodation steps (in near response)

A

para fibers contract ciliary muscle (relax suspensory ligs - become rounder)

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18
Q

ciliary muscle actions

A

contract: relax suspensory ligs - lens becomes rounder - see things close
relax: contract suspensory ligs -lens become flatter - see things far

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19
Q

convergence (in near response)

A

III innervates both medial rectus muscles –> adduct both

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20
Q

near response steps

A 
stim visual cortex
superior colliculus and pretectal nuc
EdWest
oculomotor nuc (+ ciliary gang)
III adducts both (medial rectus) (+ para constricts pupils, contract ciliary muscles)
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21
Q

Argyll Robertson pupil causes

A

neurosyphilis
pineal tumor
diabetes

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22
Q

Argyll Robertson pupil Sx

A

no direct or consensual light response

near response in tact

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23
Q

Argyll Robertson mech

A

lesion/compress pretectum

more neurons devoted to near than light response

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24
Q

Argyll Robertson AKA

A

pupillary light-near dissociation

prostitute’s pupil

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25
Q

Marcus Gunn pupil AKA

A

relative afferent

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26
Q

Marcus Gunn mech

A

optic nerve lesion

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27
Q

Marcus Gunn causes

A

MS

28
Q

Marcus Gunn Sx

A

light in affected pupil - pupils dont constrict fully
light in unaffected - pupils constrict fully
light in affected again - pupils dilate (weaker stim in II)

29
Q

Transtentorial (uncal) herniation cause

A

increased intracranial pressure

30
Q

Transtentorial (uncal) herniation mech

A

increased intracranial P –> uncal herniation –> CN III compressed –> affect para, add/elevate muslces, LPS

31
Q

Transtentorial (uncal) herniation sx

A

pupil fixed and dilated (1st)
down and out eye
ptosis

32
Q

horner syndrome mech

A

lesion of oculosymp pathway

33
Q

horner syndrome sx

A

miosis (lesion side)
ptosis
apparent enopthalmos
hemianhidrosis

34
Q

Adie pupil mech

A

ciliary gang lesion

affects highly myelinated DRGs in LL too

35
Q

Adie pupil sx

A

monocular AR pupil (dilated pupil responds sluggishly to light but responds to near response)
loss of knee jerk reflex (on side of lesion)

36
Q

fovea location, description

A

post temporal side of retina

cones only - direct access to light

37
Q

age related macular degeneration mech

A

push macula away from choroid (can’t get nutrients) –> lose macular/central vision

38
Q

layers of retina (in to out)

A

ganglion cell layer
bipolar cell layer
photoreceptors
pigment epi

39
Q

amacrine cell fxn

A

synapse w/ ganglion and bipolar cells

detect motion speed and light intensity

40
Q

horizontal cell fxn

A

enhance contrast

41
Q

rods (kinds, fxn)

A

1 kind
black/white
low-light sensitive
night vision, motion

42
Q

cones (kinds, fxn)

A

3 kinds
red, green, blue
bright light only
object recognition (edges)

43
Q

visual processing steps (in retina)

A 
rods/cones stim by light
stim bipolar cells (less)
stim ganglion cells (even less)
axons of gang cells make up optic nerve (II)
LGB
44
Q

vision steps

A
  1. retina (II) stimulated (by opp field)
    2a. temp/lat II stay ipsi
    2b. nasal/med go contra via optic chiasm
    3abc. branches to hypothalamus, pretectum and sup colliculus
  2. go to LGB
    5a. upper field go up thru parietal to cuneate gyrus of cortex
    5b. lower field go down thru temporal via meyers loop to lingual gyrus of cortex
45
Q

lesions in front of chiasm (types)

A

optic nerve

11/2 optic nerve (temp or nasal)

46
Q

lesions in front of chiasm (qualities)

A

monocular

ipsilateral

47
Q

defect from lesion of optic nerve

A

no vision in ipsilateral eye (anopia)

48
Q

defect from lesion of 1/2 optic nerve

A

temporal lesion –> no nasal vision in ipsilateral eye

nasal lesion –> no temporal vision in ipsilateral eye

49
Q

optic nerve lesion causes

A

internal carotid artery aneurysm

50
Q

chiasm lesion qualities

A

binocular
bitemporal vision loss (only nasal IIs cross)
heteronymous

51
Q

lesions in front of chiasm (causes)

A

optic neuritis

central retinal artery occlusion

52
Q

superior compression of chiasm cause

A

craniopharyngioma

53
Q

superior compression of chiasm mech and sx

A

upper quadrant of retina is superior (compressed first)

begin as inferior quadrantanopia

54
Q

inferior compression of chiasm cause

A

pituitary adenoma

55
Q

inferior compression of chiasm mech and sx

A

lower quadrant of retina is inferior (compressed first)

begin as superior quadrantanopia

56
Q

lesions past chiasm types

A

optic tract to LGB
meyer loop
parietal loop
cerebral cortex

57
Q

lesions past chiasm qualitites

A

binocular
contralateral
homonymous

58
Q

defect of optic chiasm lesion (whole)

A

bitemporal heteronymous hemianopia

can’t see on outside

59
Q

optic tract lesion mech

A

lesion ipsilateral temporal retina

lesion contalateral nasal retina

60
Q

defect in optic tract lesion

A

contralateral homonymous hemianopia

61
Q

meyer’s loop lesion mech

A

lesion ipsi lower temporal retina

lesion contra lower nasal retina

62
Q

meyers loop lesion defect

A

contra homonymous superior quadrantanopia

63
Q

parietal tract lesion mech

A

lesion ipsi upper temporal retina

lesion contra upper nasal retina

64
Q

parietal tract lesion defect

A

contra homonymous inferior quadrantanopia

65
Q

cerebral cortex defect

A

contra homonymous hemianopia w/ macular sparing (sep. blood flow)

66
Q

lesion both tracts from LGB mech

A

lesion ipsi temporal

lesion contra nasal

67
Q

lesion both tracts from LGB defect

A

contra homonymous hemianopia

Neuroscience (15 decks)

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