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neuro > Control of Eye Movements > Flashcards

Control of Eye Movements Flashcards

1
Q

medial and lateral rectus

A

adduct & abduct

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2
Q

upgaze

A

superior rectus

inferior oblique

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3
Q

down fze

A

inferior rectus

superior oblique

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4
Q

CN III exits at

A

interpedunular fossa of midbrain

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5
Q

CN IV exits at

A

(trochlear)

dorsum of brainstem - caudal midbrain and wraps around brainstem

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6
Q

CN VI

A

(abducens) brainstem- medullary pontine junction

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7
Q

ipslateral vs contralateral

A

CN IV is contralateral, rest are ipsi

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8
Q

what else travels in occulomotor nerves

A

parasymps

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9
Q

PS in occulomotor

A

arise from Edinger-Westphal nucleus–>synapse in ciliary gnaglion with post gang–>lens becomes rounder

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10
Q

compression of 3rd CN

A

pupil dilation

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11
Q

afferent projections of occulomotor

A

pretectal region

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12
Q

what is CN 3 in close contact with when comes out of interpendicular fossa

A

posterior cerebral and posterior communicating artery–> aneurysms

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13
Q

where is an area that extraoccular nerves are often damaged?

A

pituitary fossa or cavernous sinus

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14
Q

trochlear pathway

A

rostral pons/caudal midbrain (trochlear nucleus)

  • ->decussates in brainstem
  • ->exits from dorsal side brainstem at ponto-mesencephalic junction

*passes in lateral cavernous sinus

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15
Q

abducens pathway

A

caudal pons–>leaves brainstem at medullary pontine junction

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16
Q

saccadic eye movements

A

very rapid jump in eye to acquire new target or follow moving target

5th of a second processing delay

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17
Q

when extraoccular nerve damaged

A

drift TOWARDS muscle

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18
Q

voluntary eye movements

A

cerebral cortex/superior colliculus–> paramedian reticular formation

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19
Q

head turn vs saccade

A

head turns 20-40 ms after saccade

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20
Q

microsaccade

A

keeps imagine from staying on same rod or cone too long

21
Q

Voluntary Horizontal Gaze pathway

A

R frontal eye field of cerebral cortex –>right superior colliculus–decussate–>left paramedian pontine reticular formation–>left CNV1
..–> to L lateral rectus
..through MLF contralaterally to right CN III–>R medial rectus

TOWARDS the PPRF involved (towards left)

22
Q

sensory aspect of superior colliculus

A

retina (vision)
inferior colliculus (sound)
spinal cord (somatic sensation)
cerebral cortex

23
Q

motor aspect of superior colliculus

A

eye/head movements

from spinal cord (tectospinal tract) & brainstem (tectoreticular tract)

24
Q

medial longitudinal funiculus

A

interconnects nuclei of extraoccular muscles to coordinate conjugate eye movements

25
Q

damage to MLF

A

internuclear opthalmoplegia

eye movement laterally is not followed by medial movement of other eye

26
Q

voluntary vertical gaze pathway

A

diffuse areas of cerebral cortex
–>rostral interstital nucleus
–> posterior commissure for upgaze
OR –>CN III and IV

27
Q

parinaud-Syndrome

A

eyes retract in back of head when try to look up

–>due to pressure from expanding mass dorsal to midbrain

28
Q

Progressive supranuclear palsy

A

patient cant look up or down voluntarilly, but when head is flexed or extended, eyes can move in these directions

degenreation of vertical gaze center

29
Q

vertical gaze center

A

rostral interstitial nucleus

30
Q

vestibulooccular reflex

A

eye movements in response to change in head

31
Q

vestibuloccular reflex pathway

A 
CNVII
-->flocculus -->vestibular nucleus
OR -->vestibular nucleus
-->CN VI, PPRF
--MLF-->CN III, IV
32
Q

damage to vestibuloccular reflex

A

nystagmus

  • -drift of eyes as if eyes head was moving
  • -triggers rapid saccadic eye movement to original target
    • jerky, repetitive eye movement
33
Q

tracking

A

eyes move smoothly only when you are tracking or when your head is moving

voluntarily but needs a stimulus

34
Q

smooth pursuit/tracking pathway

A 
occipital eye field
-->pontine nucleus
OR -->frontal eye movt-->pontine nucleus
-->middle cerebellar peduncle
-->contralateral flocculus
-->inferior cerebral peduncle
-->ipsilateral vestibular complex
-->CN VI, PPRF (bilaterally)
--MLF-->CN III, CN IV
35
Q

occipital eye fields are not

A

well defined in occipital lobe
–region near junction of occipital lobes with posterior parietal and temporal lobe

includes areas involved in interpreting movement of objects

36
Q

fixation and optokinetic reflexes

A

use same wiring as smooth pursuit

37
Q

fixation

A

ability to fixate on a moving target

–complements vestibulooccular to stabilize eyes

38
Q

optokinetic

A

involves fixation on objects that are moving in relation to the head
(like when moving in a car)-eyes tracking object involuntarily for a distance and saccade in opposite direction to re-aqcuire target

39
Q

if one visua cortex is damage

A

opto is damaged in that nystagmus is lost when bjects move TOWRDS side of damaged cortex lesion (away from side of vision loss)

40
Q

vergence

A

convergence or divergence of eyes in order to focus close-up or off in a distance

41
Q

vergence pathway

A

occipital cortical projections–>vergence center in mesencephalic RF

42
Q

vergence is wire in parallel with

A

accomodation

–pupillary constriction and contraction of cillary muscle occurs at same time to allow for close focus

43
Q

pupillary light reflex

A

bilateral constriction of pupil in response to light stimulus

R retina–>R pretectal nuclei–>R edinger westphal OR L edinger westphal (through posterior commissure)

44
Q

pendular nystagmus

A

oscillations equal in both directions

NOT due to CNS or vestibular damage

45
Q

jerk nystagmus

A

slow and fast component

indicates problem with vestibular system (iinner ear nerves, nerves to flocculus, vest nuclei, MLF)

46
Q

slow component is

A

imbalance in vestibular nuclei

47
Q

fast component

A

awareness of cerebral cortex and evoke fixation

48
Q

vertical gaze center

A

rostral interstial nucleus of MLF

49
Q

horizontal gaze center

A

PPRFe

neuro (9 decks)

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