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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
Marcus Gunn pupil AKA
relative afferent
26
Marcus Gunn mech
optic nerve lesion
27
Marcus Gunn causes
MS
28
Marcus Gunn Sx
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
Transtentorial (uncal) herniation cause
increased intracranial pressure
30
Transtentorial (uncal) herniation mech
increased intracranial P --> uncal herniation --> CN III compressed --> affect para, add/elevate muslces, LPS
31
Transtentorial (uncal) herniation sx
pupil fixed and dilated (1st) down and out eye ptosis
32
horner syndrome mech
lesion of oculosymp pathway
33
horner syndrome sx
miosis (lesion side) ptosis apparent enopthalmos hemianhidrosis
34
Adie pupil mech
ciliary gang lesion | affects highly myelinated DRGs in LL too
35
Adie pupil sx
monocular AR pupil (dilated pupil responds sluggishly to light but responds to near response) loss of knee jerk reflex (on side of lesion)
36
fovea location, description
post temporal side of retina | cones only - direct access to light
37
age related macular degeneration mech
push macula away from choroid (can't get nutrients) --> lose macular/central vision
38
layers of retina (in to out)
ganglion cell layer bipolar cell layer photoreceptors pigment epi
39
amacrine cell fxn
synapse w/ ganglion and bipolar cells | detect motion speed and light intensity
40
horizontal cell fxn
enhance contrast
41
rods (kinds, fxn)
1 kind black/white low-light sensitive night vision, motion
42
cones (kinds, fxn)
3 kinds red, green, blue bright light only object recognition (edges)
43
visual processing steps (in retina)
``` 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
vision steps
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 4. 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
lesions in front of chiasm (types)
optic nerve | 11/2 optic nerve (temp or nasal)
46
lesions in front of chiasm (qualities)
monocular | ipsilateral
47
defect from lesion of optic nerve
no vision in ipsilateral eye (anopia)
48
defect from lesion of 1/2 optic nerve
temporal lesion --> no nasal vision in ipsilateral eye | nasal lesion --> no temporal vision in ipsilateral eye
49
optic nerve lesion causes
internal carotid artery aneurysm
50
chiasm lesion qualities
binocular bitemporal vision loss (only nasal IIs cross) heteronymous
51
lesions in front of chiasm (causes)
optic neuritis | central retinal artery occlusion
52
superior compression of chiasm cause
craniopharyngioma
53
superior compression of chiasm mech and sx
upper quadrant of retina is superior (compressed first) | begin as inferior quadrantanopia
54
inferior compression of chiasm cause
pituitary adenoma
55
inferior compression of chiasm mech and sx
lower quadrant of retina is inferior (compressed first) | begin as superior quadrantanopia
56
lesions past chiasm types
optic tract to LGB meyer loop parietal loop cerebral cortex
57
lesions past chiasm qualitites
binocular contralateral homonymous
58
defect of optic chiasm lesion (whole)
bitemporal heteronymous hemianopia | can't see on outside
59
optic tract lesion mech
lesion ipsilateral temporal retina | lesion contalateral nasal retina
60
defect in optic tract lesion
contralateral homonymous hemianopia
61
meyer's loop lesion mech
lesion ipsi lower temporal retina | lesion contra lower nasal retina
62
meyers loop lesion defect
contra homonymous superior quadrantanopia
63
parietal tract lesion mech
lesion ipsi upper temporal retina | lesion contra upper nasal retina
64
parietal tract lesion defect
contra homonymous inferior quadrantanopia
65
cerebral cortex defect
contra homonymous hemianopia w/ macular sparing (sep. blood flow)
66
lesion both tracts from LGB mech
lesion ipsi temporal | lesion contra nasal
67
lesion both tracts from LGB defect
contra homonymous hemianopia

Neuroscience (15 decks)

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