EYE MOVEMENTS - MODULE Flashcards

1
Q

Which 3 cranial nerves innervate the extraocular muscles

A
  • Abducens (CN VI)
  • Trochlear (CN IV)
  • Oculomotor (CN III)
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2
Q

What muscle is innervated by the abducens nerve

A

Lateral rectus

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3
Q

what muscle is innervated by the trochlear nerve

A

superior oblique

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4
Q

what muscle(s) are innervated by the oculomotor nerve

A
  • Superior rectus
  • medial rectus
  • inferior rectus
  • inferior oblique
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5
Q

What is gaze

A

the coordinated movements of the right and left eyes to a visual target

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6
Q

How does communication between ocular nuclei occur

A

via the ascending medial longitudinal fasciculus

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7
Q

what is the medial longitudinal fasciculus

A

a fiber tract that is critical for coordianted eye movements

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8
Q

Where is the vertical gaze center located

A

in the midbrain reticular formation and pretectal area

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9
Q

where is the horizontal gaze center located

A

in the pons - paramedian pontine reticular formation

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10
Q

The horizontal gaze center gives input to the ____ to direct gaze to the _____

A

abducens nucleus

ipsilateral side

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11
Q

A subset of neurons projects from the abducens nucleus to what muscle

A

ipsilateral lateral rectus

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12
Q

A second subset of neurons projects from the abducens nucleus to the ___ and the to what muscle

A

oculomotor nucleus

left medial rectus muscle

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13
Q

What are saccades? What do they allow us to do?

A

rapid, simultaneous movements of the eyes that redirect the gaze between different fixation points
Allow us to scan the environmetn

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14
Q

what are reflexive saccades

A

visually guides sacced in response to external cue

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15
Q

What are volitional saccades

A

voluntary eye movements indenpendent of any visual stimulus

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16
Q

saccadic eye movement can be initiated by ___ or ____

A

cortical or subcortical areas of the brain

17
Q

Cortical initiation of saccades comes from..

A

frontal eye fields located in the supplementary motor areas and extending anteriorly

18
Q

Cortical initiation of saccades is the main input for..

A

volitional saccades

19
Q

subcortical initiation of saccades comes from?

A

superior colliculus located in the posterior midbrain

20
Q

subcortical initiation of saccade is the main input for…

A

reflexive saccades

21
Q

What is the pathway for reflexive saccades

- this card is frigged im sorry

A
  • Visual stimulus appear in visual field and active contralateral frontal eye field and the contralateral superior colliculus
  • within the superior colliculus, neurons in the superficial visual layer are activated and project to corresponding neurons in the deep motor layers
  • neurons from superior colliculus activate contralateral horizontal gaze center which then initiated gaze in ipsilateral direction
22
Q

The descending MLF allows communication between…

A

nuclei and the brainstem

23
Q

the descending MLF comprises the ___ and ____

A

medial and lateral vestibulospinal tracts

24
Q

The desceding MLF arises from the ____ and influences

A

Vestibular nuclei and influences muscle tone for balance and posture and it critical in the positioning of the head and neck

25
In smooth pursuit the 1st step is for the primary visual cortex and the frontal eye fiels to send projections to the...
ipsilateral pontine nuclei
26
in smooth pursuit, fibres from the pontine nuclei project across the midlines into ...
the contralateral cerebellum
27
In smooth pursuit fibres project from the cerebellum to the...
ipsilateral vestibular nuclei
28
in smooth pursuit, fibres from the vestibular nuclei cross the midline and project tooo....
the contralateral abducens nucleus
29
what is the end goal of smooth pursuit
to coordinate movement of both eyes to look in the same direction
30
What is the vestibulo-ocular reflex
rapid adjustment of eye movement in response to movement of the head (to counteract it)
31
why do we need to have the vestibulo-ocular reflex
to stabilize image on the retina and prevent the image blurring
32
how many dimensions does the vestibo-ocular reflex occur in
3 dimensions
33
what initiates the VOR
shifting of fluid in the horizontal canal (shifts opposite to head movement)
34
during the VOR when fluid shifts in the horizontal canal what is activated
sensory cells
35
in the VOR, the sensory cells once activate project to ...
the ipsilateral vestibular nuclei
36
in the VOR, fibres from the vestibular nuclei cross the midline and project to the
contralateral abducens nucleus
37
in the VOR eyes move in what direction
opposite to the head movement