9-Ocular Motility Flashcards Preview

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Flashcards in 9-Ocular Motility Deck (70):
1

Primary position of the eyes

Eyes fixate straight ahead and eyes and head are straight

2

Secondary position

Around the X ad Z axes of Fick. Purely vertical or horizontal

3

Tertiary position

Y axis and head tilt positions

4

How many cardinal positions do we have

6

5

What are cardinal positions

Positions where only 1 muscle in each eye is responsible for movement

6

What is the field of action

The gaze where the effect of a muscle is best observed

7

Any weakness of the SO can be seen as what

Depression in adduction

8

Why I'd the field of action important

Is helps you isolate if a deviation seen is weakness of that muscle, a restriction of action from the antagonist, or both

9

What is agonist antagonist of motility

Pair of muscles in the SAME eye that move in opposite direction

10

What are synergistic muscles

Muscles in the SAME eye that move in the SAME direction

11

What are yoke muscles

Pair of muscles, one in each eye, the produce conjugate eye movements (move eye in same direction)

12

What is the Sherrington law of reciprocal innervation

Increased innervation to on e muscle is accompanied by a decrease innervation to its antagonist in the same eye

13

What is the hering law of equal innervation

During conjugate eye movements, equal and simultaneous innervation flow to yoked muscles

14

Due to Herings law of equal innervation what will you see if there is a palsy in one muscle

The yoke muscle in the other eye will over react

15

What muscles are important for horizontal versions

Vertical rectus muscles and oblique muscles

16

What muscles are important for vertical versions

Horizontal rectus muscles

17

Primary deviation

Unaffected eye fixates

18

Secondary deviation:

Restricted eye fixates

19

Which is bigger a primary or secondary deviation?

Secondary, because there is increased innervation to move the affected eye

20

T/F Increase innervation goes to the non-fixating eye that causes excessive action and a larger deviation

True

21

Ductions

Movement of one eye sound the axes of Fick

Monocular

22

Versions

Binocular
Simultaneous and conjugate eye movements or rotation of both eyes

23

What are conjugate eye movements

Both eyes move in the same direction and same amount

24

Vergences are

Disconjugate eye movements where the eyes rotate or move in opposite directions

25

What are vergences important for

Fusion

26

Convergence

Both eyes rotate in

27

Divergence

Both eyes rotate out

28

Incyclovergence

Rotation of the superior portion of the eyes in

29

Excyclovergence is

Rotation of superior portion of both eyes out

30

T/F versions and vergences have similar late cites?

True

31

Which is faster acting movements? Versions or vergences?

Versions are faster

32

What is the infranuclear control

Cranial nerves (3,4,5) and the muscles they innervate

33

What is nuclear control

The cranial nuclei

34

What is Supranuclear control

Higher order sensory and motor system that plans and controls eye movements
Cerebral cortex, cerebellum, brainstem

35

What control system controls versions and vergences?

Supranuclear

36

What eye movements are included in versions?

Saccades
Pursuits
VOR
OKN
OKR

37

What are saccades?

Fast conjugate eye movements that work to keep images on the fovea. They require a strong force

38

What is the latency for saccades?

120-200 ms

39

When are saccades developed

1 year of age

40

Are saccades voluntary?

Yes, but they can be reflexive

41

What are pursuits?

Following eye movements

42

What is the latency for pursuits

125 ms

43

What is the peak velocity for pursuits

30-60 degrees per sec

44

What do pursuits match up

Eye velocity to target velocity

45

Are pursuits voluntary or involuntary

Involuntary

46

When do pursuits develop

3-4 months of life

47

What controls pursuits

Parietal lobe on same side

48

What are vestibule-ocular reflex (VOR)

Movements that stabilize a retinal image during brief head movements

49

What can the VOR be seen in

Dolls head maneuver

50

When do VOR develop

Horizontal at birth
Vertical is later

51

What is seen on dolls head maneuver (eye movement)

Eye moves opposite of head movement

52

What causes horizontal nystagmus

Vestibular damage

53

When is dolls head maneuver contraindicated

In trauma where spinal/cervical injuries

54

What is the caloric test? How does the eye move with different temperature water

Test that uses warm and cold water to set up a temperature gradient in the semicircular canals. Cold water the eye moves to opposite ear. Warm water it moves toward the same ear that water was injected in.

COWS

55

What is OKR responsible for

Continuous eye movements. It kicks in after VOR response fades with continuous head movements

56

What is rotational testing? What does it show?

Spin patient in a chair for about 20 seconds. Eyes will move in fast phase in opposite direction of rotation

57

What is OKN

Slow pursuit eye movement followed by fast corrective saccades. The head is still. It requires inpu from the visual system.
Has a longer latency

58

When is OKN developed

3-5 months

59

When is OKN used

In malingering, and cooperative patients

60

What does a + OKN tell you

That VA is at or better than the size of the stripes on OKN drum

61

What does a - OKN tell you

Nothing

62

How is OKN tested

With an OKN drum. Horizontal and vertical

63

Slide 33

Big chart

64

What do vergences ensure

Bifoveal fusion

65

What is fusional vergences

It requires the attention and cooperation of the cerebral cortex

66

What is tonic vergence

Constant innervaton tone to the EOMs when awake and alert. To keep the eyes straight forward because the eyes are naturally diverging.

67

What is proximal vergences

Induced due to awareness of near

68

What are accommodative vergences

Consistent increment of accommodative convergence with each dipter of accommodation gives AC/A ratio

69

What does a high AC/A produce

ET with accommodation

70

What dies a low AC/A do

Makes it harder to converge, less esotropic, more exotropic