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Block 5 Week 3 Dani > Kenyon-Eye movements > Flashcards

Kenyon-Eye movements Flashcards

1
Q

Dysfunction with eye postion is typically caused how?

A

via lesions in brainstem or cranial nerves

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2
Q

Adults with leasions in the extraocular muscles or their nerves have (blank)

A

diplopia (double vision)

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3
Q

Infants and children with lesions in the extraocular muscles or their nerves have (blank) that can result in loss of function in the affected eye.

A

strabismus

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4
Q

Where do you find lower motor neurons?

A

cell bodies in the brainstem or spinal cord

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5
Q

Where do lower motor neuron axons end?

A

in neuromuscular junctions with skeletal fibers

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6
Q

Are lower motor neurons excitatory or inhibitory and via what neurotransmitter and receptor?

A

excitatory via Ach and Nictonic muscle receptors

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7
Q

What are upper motor neurosn and where do their axons end and are they excitatory or inhibitory?

A

cell bodies in the brainstem or cerebral cortex, axon end in synapses on other upper motor neurons, local circuit neurons, lower motor neurosn or some combo
The are both excitatory and inhibitory

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8
Q

What are the three nuclei of the brainstem that controls external muscles of the eye?

A

oculomotor III
trochlear IV
abducens VI

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9
Q

Injruy to the brainstem (trauma, ischemia, etc) will cause defects in (blank) positioning that reveal the location of the injury

A

eye positioning

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10
Q

Where does the superior oblique muscle attach on the eyeball?

A

back

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11
Q

Contraction of the superior oblique does what to the eye?

A

causes depression and medial rotation

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12
Q

How can you get torsion (rotates eyeball inward) without depression?

A

superior rectus

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13
Q

T or F

the effect of the superior oblique muscle varies with direction of the eye.

A

T

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14
Q

With abduction of the eyeball, contraction of the superior oblique does more (blank)

A

intorsion

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15
Q

With ADduction of the eyeball, contraction of the superior oblique does more (blank)

A

depression

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16
Q

There are (blank) in brainstem nuclei that go to the extraocular ey muscles and are controlled by local circuit neurons and upper motor neurons located in brainstem and cortex

A

lower (alpha) motor neurons

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17
Q

Do you find at the end of motor end plates?

A

acetylcholine, nicotinic ACh receptors

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18
Q

In the extraocular eye muscles, 1 motor neuron activates (blank) muscle fibers

A

3

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19
Q

THe oculomotor nerve has what kind of fibers?

A

somatic and autonomic

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20
Q

this nerve contains axons of motor neurons to the external muscles of the ipsilateral eye that are not served by 4 or 6 and axons of motor neurons to somatic muscle of eyelid and autonomic axons to pupil (ipsilateral)

A

Oculomotor (III)

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21
Q

The trochlear nerve contains axons that are ipsilateral or contralateral to superior oblique?
Does it contain somatic or autonomic fibers?

A

contralateral

somatic

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22
Q

The abducens nerve gives motor neurons to ipsilateral or contralateral lateral rectus?

A

ipsilateral

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23
Q

The trochlear nerve exits the dorsal surface of the midbrain and (blanks).

A

crosses over

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24
Q

Can you get a legion that messes up both trochlear nuclei? Does it have to be big to do so? Does this happen often?

A

yes
nope
nope

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25
Q

what happens if you get a legion on your trochlear nerve?

A

paralysis of superior oblique muscles (lower motor neuron syndrome)
diplopia on looking downwards (super hard to get up stairs)

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26
Q

How do you compensate for you messed up superior oblique muscle that is making you get diplopia when looking down?

A

you tilt your head toward the weak muscle (i.e if you have a legion in the left eye, you will put your right ear to your right shoulder to compensate)

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27
Q

How does the abducense nerve travel from the abducens nuclei in the pons.

A

abducens nerve comes out of abducens nuclei to the ipsilateral lateral rectus muscle (DOES NOT CROSS OVER)

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28
Q

What is the most common palsy? why?

A

CN 6 palsy, because the course of the nerve is sooooo long

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29
Q

What happens if you lose your CN 6

A

you get paralysis of LR and you get failure of abduction on affected eye and can intort causing double vision

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30
Q

How do people with CN 6 compensate for the lack of abduction and increased intorsion?

A

rotation of head

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31
Q

Why do you get intorsion when you lose your abducens nerve?

A

because of the unopposed action trochlear nerve (superior oblique causes intorsion)

32
Q

How does the oculomotor nerve travel from the midbrain?

A

from the oculomotor nucleus

to ipsilateral superior, inferior and medial rectus and to inferior oblique (NO CROSSOVER)

33
Q

Where is the oculomotor nucleus located?

A

under superior colliculus

34
Q

Neurons in the (blank) nucleus also innervate the levator muscles of the eyelid

A

oculomotor nucleus

35
Q

What extraocular nerve carries axons from edinger-westphal nucleus? What does this mean?

A

oculomotor nerve

oculomotor nerve allows for pupillary contriction via sympathetics that travel on it via the edinger westphal nucleus

36
Q

What does your eye look like if you lose your oculomotor nerve?

A

Down and out (cuz of unopposed action of superior oblique and lateral rectus muscle)
Drooping of eyelid
dilated pupils
paralysis of accomodation

37
Q

What is the near reflex triad test and what does it do?

A

it tests oculomotor nerve functionby looking at vergence adductioon of eyeballs, accomodation of the lens, pupillary restriction

38
Q

What are the four types of eye movements?

A

saccades
smooth pursuit
vergence
vestibulo-ocular eye movements

39
Q

What are saccades?

A

rapid ballistic movements that put an image on the fovea

40
Q

What are smooth pursuit movements?

A

slow tracking movements that keep a moving image on the fovea (voluntary) I.e keep a moving target on the fovea

41
Q

What are vergence movements?

A

aligning the fovea with targets at different distances (tracking something moving toward or away from you) AND
moves the eye in opposite directions (conjugate movements) so that the image is positioned in both foveas

42
Q

What do vestibulo-ocular movements do?

A

compensate for movements of the head driven by the vestibular system. I.e vestibulo-ocular movements hold images stable during brief head movements

43
Q

The semicircular canals detect (blank) of the head.This info is used to direct the eyeballs to move in the (blank) direction (i.e to maintain the field of view)

A

rotation

opposite

44
Q

When do the vestibuloocular movements work best?

A

during acceleration or rapid rotation (i.e movements that are too fast and abrupt for tracking)

45
Q

The (blank) the movements the more important vestibulo-ocular system becomes

A

quicker

46
Q

During constant or slow rotation, vestibulo-ocular compensatory eye movements cease after (blank) seconds.

A

30 (visual cues will then be important)

47
Q

the quicker the movement, the more important the (blank) system

A

vestibulo-ocular

48
Q

T/F: Each semicircular canal transmits a tonic signal to the vestibular nerve even when the eyes are still

A

T

49
Q

t/F: An imbalance in the signals from the vestibular system will result in nystagmus when the head is still.

A

T

50
Q

T/F: Saccades are both voluntary and reflexive.

A

T; reflexive: seeing something coming at you from your periphery; voluntary: looking at individual parts of an image

51
Q

T/F: the eye movements in REM sleep are saccades

A

True

52
Q

the amplitude of the saccade correlates with the (length/amplitude) of the burst of action potentials going to eye muscles

A

length of duration of burst of AP’s

53
Q

As the eye moves more laterally, the baseline firing of the lateral rectus (inc/dec/stays the same)

A

increases

54
Q

In what three nuclei are the lower motor neurons of the eye located?

A
  1. Oculomotor
  2. Trochlear
  3. Abducens
55
Q

The PPRF/reticular center is the (horizontal/vertical? gaze center

A

horizontal

56
Q

Both of the gaze centers are in the (blank) formation

A

reticular formation

57
Q

The horizontal and vertical gaze centers contain the (blank) motor neurons which talk to the oculomotor, trochlear, and abducens

A

upper motor neurons

58
Q

T/F: the lateral rectus is directly innervated by lower motor neurons in the abducens nucleus

A

T

59
Q

T/F: there are interneurons present in the abducens nucleus

A

T

60
Q

Where do the internuerons of the R abducens nucleus head? What tract do they travel on?

A

They go to the L oculomotor nucleus via the medial longitudinal fasciculus

61
Q

T/F: the portion of the medial longitudinal fasciculus between abducens and oculomotor is a local circuit neurons

A

T

62
Q

Nuerons in the PPRF drive inhibitory interneurons (local circuit) that synapse in the (ipsi/contra) abducens

A

contralateral abducens

63
Q

Upper motor neurons found in which two structures are used in saccade targeting?

A

Superior colliculus (midbrain and frontal eye field (frontal lobe)

64
Q

Light on a particular spot on the retina can be mapped to a particular spot on the (sup colliculus/frontal eye field)

A

superior colliculus

65
Q

Motor neurons in the sup colliculus will drive the eye to move the image to the (blank)

A

fovea

66
Q

Are saccades used to move eyes to a specific target or used to move eyes in a specific motion or amount?

A

To a specific target

67
Q

T/F: the parietal lobe is used in commanding saccades

A

True! Besides sup colliculus and FEF, the occipital lobe (vision) and parts of parietal control visual upper motor neurons

68
Q

Besides the retinal mapping on the sup colliculus, what two other senses are also mapped there?

A

Auditory and somatic stimuli, so you can look quickly at something you see or hear!

69
Q

Does the FEF have multiple paths to the PPRF?

A

Yes

70
Q

What tract does the FEF take to the sup colliculus?

A

corticobulbar

71
Q

T/F: partial damage in a center between the FEF and the PPRF can be compensated

A

T

72
Q

Smooth pursuit movements are driven through which gaze center?

A

horizontal

73
Q

T/F: the parietal and occipital lobes are necessary for smooth pursuit

A

true

74
Q

T/F: the occipital and parietal lobes generate the slow phase of optokinetic nystagmus

A

T

75
Q

Discuss the construction of a stable image. We’re always moving our eyes, so how do we look at anything and get a clear picture?

A

The visual centers know what commands were sent to the eyes and uses this information to construct a stable image from multiple “snaphsots”

Block 5 Week 3 Dani (12 decks)

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