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aNeuro Exam 3- Lindsey's > Eye Movements > Flashcards

Flashcards in Eye Movements Deck (55):
1

What is the representation of the optic disk in the visual field?

the blind spot

2

This is moving the fovea to an object closer (convergence) or farther away (divergence).

vergence

3

What signals the rotation of the head?

the semicircular canals

4

Saccades can be voluntarily generated by the _____.

frontal eye field (FEF)

5

The oculomotor system is subject to modulation by the ____ and ____.

cerebellum; basal ganglia

6

What is inhibited during conjugate gaze?

antagonist motor neurons

7

When is nystagmus normal?

when the head is rotated for along time or when there is a moving visual stimulus

8

What initiate conjugate eye movements?

a variety of sensory inputs, especial visual and vestibular

9

What are the 2 important control centers for saccades?

  1. the cortex
  2. the superior colliculus

10

If the head turns to the right, the eyes ____.

counter rotate to the L

11

Smooth pursuit can only maintain foveation at a rate of about _____.

50 degrees/second

12

The direction of the nystagmus is defined by _____.

the direction of the rapid saccade

13

What are saccades?

rapid, ballistic eye movements (to bring an object onto the fovea)

14

Where is the pattern generator for horizontal saccades?

in the reticular formation near the abducens nucleus (the paramedian pontine reticular formation- PPRF)

15

What eye condition do MS patients often get?

internuclear ophthalmoplegia (INO)

16

Cells in the vestibular nuclei project by way of the ______ to excite lateral rectus motor neurons in the abducens nucleus.

medial longitudinal fasciculus (MLF)

17

Saccades can be reflexively directed from the _____.

parietal eye field (PEF)

18

If the frontal eye field is damaged, the is a _____.

temporary loss of the ability to generate saccades

19

Interruption of the _____ can cause discoordination of medial and lateral recti muscles during horizontal gaze movements, called internuclear ophthalmoplegia (INO).

medial longitudinal fasciculus (MLF)

20

Coordinate contraction of the 2 eyes is accomplished by _____ that reside in the vicinity of the oculomotor and abducens nuclei.

interneuronal pattern generators

21

What is an example of a vergence movement?

when both eyes turn towards the nose for near reading

22

Horizontal saccades are driven ____.

contralaterally

23

What are the vestibular ocular reflex (VOR) and optokinetic nystagmus (OKN) eye movements?

a combination of pursuit and saccades

24

What is the frontal eye field?

an area near the motor cortex that activates saccades via the reticular formation and/or the superior colliculus

25

Who often gets internuclear ophthalmoplegia (INO)?

MS patients

26

What is vergence?

moving the fovea to an object closer (convergence) or farther away (divergence)

27

Interruption of the medial longitudinal fasciculus (MLF) can cause ______, called internuclear ophthalmoplegia (INO).

discoordination of medial and lateral recti muscles during horizontal gaze movements

28

What are microsaccades?

the eye moving in small jumps to refresh the image several times/sec so it is never stabilized

29

The medial longitudinal fasciculus (MLF) is especially vulnerable to interruption bc of _____.

its length

30

Movement brings the fovea to an area that was being analyzed by _____.

that side of the brain

31

More complex eye movements are programmed in specialized regions of ____.

the neocortex

32

What muscles are responsible for horizontal rotation?

the lateral and medial rectus

33

What CN innervates the lateral rectus?

CN6

34

If the superior colliculus is damaged, ______.

saccades are less accurate and occur less often

35

If the head continues to turn, the eyes rotate slowly until the limit of eye rotation is reached, then they _____.

snap quickly back to a new fixation point

36

What are vergence movements?

eye movements in opposite directions

37

What happens physiologically during the near/accommodation reflex?

  • contraction of the medial recti
  • pupil constriction
  • ciliary muscle constriction

38

What are conjugate movements?

when both eyes move in the same direction

39

Interruption of the medial longitudinal fasciculus (MLF) can cause discoordination of medial and lateral recti muscles during horizontal gaze movements, called ______.

internuclear ophthalmoplegia (INO)

40

For stimuli moving faster than 50 degrees/second, a combination of _____ and ____ is used.

saccades and smooth pursuit

41

Where is the blind spot located in the visual field?

15 degrees lateral

42

These are rapid, ballistic eye movements (to bring an object onto the fovea).

saccades

43

Where is the pattern generator for vertical saccades?

near the oculomotor nuclei

44

Any stimuli that excites the abdences also excites the ____.

internuclear interneurons

45

What are the 4 types of eye movements?

  1. smooth pursuit
  2. saccades
  3. vestibular ocular reflex (VOR) and optokinetic nystagmus (OKN)
  4. vergence

46

When is nystagmus abnormal?

due to damage of the vestibular system or cerebellum

47

What CN innervates the medial rectus?

CN3

48

This is tracking to keep an object on the fovea.

smooth pursuit

49

If BOTH the frontal eye field and the superior colliculus are damaged, _____.

there is a permanent loss of the ability to make saccades

50

The eye moves in small jumps called _____.

microsaccades

51

Voluntary eye movements are driven by the _____.

frontal lobes

52

These eye movements are a combination of pursuit and saccades.

the vestibular ocular reflex (VOR) and optokinetic nystagmus (OKN)

53

What do saccadic eye movements activate via the superior colliculus?

the brainstem gaze center (BGC)

54

During conjugate gaze to the left, the left lateral rectus and the right medial rectus muscles are _____ and the left medial rectus and right lateral rectus are ______.

activated; inhibited

55

What is smooth pursuit?

tracking to keep an object on the fovea