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Motility Block 9 > Ocular Motility > Flashcards

Ocular Motility Flashcards

1
Q

Due to the direction of a muscles pull around the axes

A

Muscle action

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2
Q

Major effect on the position of the eye when the muscle contracts while the head is in primary position

A

Primary action

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3
Q

The additional effect a muscle has on the position of the eye

A

Secondary and tertiary action

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4
Q

Position of the eyes when fixating straight ahead. The eyes and head are both straight

A

Primary gaze

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5
Q

Around the X and Z axes of Fick (straight up, down, left and right). Purely vertical or horizaontal

A

Secondary positions

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6
Q

The Y axis (oblique muscle positions) as well as head tilt positions

A

Tertiary positions

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7
Q

How many cardinal positions

A

6

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8
Q

Why is primary gaze not a cardinal position?

A

Multiple muscles being used

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9
Q

Which gazes are cardinal gazes

A

Right secondary
Left secondary
All tertiary gazes

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10
Q

Positions where only 1 muscle in each eye is responsible for movements (in addition to the yoked muscle in the other eye)

A

Cardinal positions

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11
Q

The gaze position (one of the cardinal positions) where the effect of a muscle is best observed

A

Field of action

SR in OD is up and to the right

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12
Q

By moveing the field of action,

A

You can isolate and evaluate each muscle. This is where the muscle axis is parallel or perpendicular to the visual axis

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13
Q

What will the field of action always be

A

Cardinal

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14
Q

What two muscles give you pure primary action when the visual axis and the orbital axis are aligned at 23 degrees

A

IR and SR

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15
Q

What is the field of action for SR

A

23 degrees abducted, elevator

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16
Q

Doing what to the superior rectus makes it perpendicular to the muscle plane, becomes and intortor?

A

Adduction 67 degrees

Makes it 90 degrees to the muscle plane

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17
Q

Field of action for inferior rectus

A

Down and to the right (abducted 23 degrees) to make it a depressor

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18
Q

Doing what it the inferior rectus makes it an extortor

A

Adduction 67 degrees

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19
Q

Is the field of action always the same as the muscle action?

A

No

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20
Q

Examples of why the field of action is not always the same as muscle action

A

SO intorts, depresses, and abducts
-but depression by the SO is best seen in the ADDuction position. When the eye is aDDucted 51 degrees, the Visual axis and the direction of the muscle coincide. This the best position to evaluate the SO

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21
Q

Any weakness of the superior oblique can be seen as a

A

Depression in ADDUction

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22
Q

What does field of action help you do

A

Helps you to isolate if a deviation seen is from weakness of that muscles, a restriction of action from the antagonist or both

23
Q

What are the RSRs field of action

A

Up and to the right, but the actions of the SR are elevation, intorsion, and adduction

24
Q

Muscle plane/insertion of the SR and IR

A

Are along the orbital axes and the orbital axis is 23 degrees of the visual axis

25
Q

Pair of muscle in the SAME eye that move the eye in opposite directions

A

Agonist-antagonist

-MR is the antagonist of the LR

26
Q

Muscles in the same eye that move the eye in the same direction

A

Synergistic muscle

  • IO and SR
  • SO-IR
27
Q

Pair of muscles, one in each eye, that produces conjugate eye movements (moves the eyes in the same directions)

A

Yoke muscles

-up and to the right is SR (OD), IO(OS)

28
Q

The right inferior oblique is the yoked muscle of the left

A

Superior rectus

29
Q

Increased innervation (and contraction) to one muscle is accompanies by a reciprocal decreases innervation to its antagonist in the SAME eye. Increased innervation to the LMR to contract makes the LLR relax. This helps in both versions and vergences

A

Sherrington law of reciprocal innervation

30
Q

Sherrington law of reciprocal innervation for secondary left gaze

A

RMR has increased innervation while RLR does not. LLR has increased innervation while LMR does not

31
Q

Sherrington law of reciprocal innervation for vergence eye movements

A

RMR has increased innervation while RLR does not, LMR has increases innervation while LLR does not one vergence eye movement

32
Q

Sherrington law of reciprocal innervation for left head tilt

A

RIO and RIR have innervation to extort while RSO and RSR do not. LSO and LSR have innervation to intort OS while LIO and LIR do not

33
Q

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

A

Hering law of equal innervation

34
Q

What law applies to innervation of yoked muscles

A

Hering law

35
Q

When will you notice that the yoke muscle in the other eye reacting

A

When there is a palsy to a muscles

36
Q

Hering law of Raquel innervation on secondary left gaze

A

RMR has increased innervation and LLR has increased innervation

37
Q

Hering law of equal innervation for head tilt to the left

A

RIO and RIR have increased innervation and LSO and LSR have the same innervation to the left eye

38
Q

The vertical rectus muscles and the oblique muscles are important to do what to prevent vertical deviations or torsional movements

A

Adjust their tone

39
Q

During vertical and oblique versions, _________ stabilize the line of sight and prevent horizontal movements

A

Horizontal rectus muscles

40
Q

The amount of innervation depends on

A

The fixating eye, the angle of deviation will vary based on which eye is fixating

41
Q

When the unaffected eye is fixating

A

Primary deviation

Good eye is still fixating

42
Q

When the paretic or restricted eye is fixating

A

Secondary deviation

Bad eye is fixating, this deviation will be bigger than primary because they have to have more innervation to do this

43
Q

Why is a secondary deviation larger than a primary deviation

A

Because there is an increased innervation to move the paretic eye to fixation. The increased innervation also goes to the non-fixating eye which causes an excessive action and a larger deviation

44
Q

Left lateral rectus palsy

A

Left eye will be turned in. If right eye is fixating, the left eye turns in because of the unopposed action of the antagonist (LMR). This is Sherrington law! This misalignment is a primary deviation

45
Q

If the paretic eye is fixating in a left lateral rectus palsy

A

Additional innervation to the left lateral rectus to establish this. But an equal increased innervation also flows to the right medial rectus because of Hering law producing an excessive adduction of the right eye. This deviation is a secondary deviation and it will be greater than the primary deviation

46
Q

Movement or rotation of one eye around the axes of Fick (monocular)

A

Duction

Evaluated with the other eye closed and having the patient move the eye in all directions of gaze

47
Q

Binocular simultaneous and conjugate eye movements or rotation of both eyes

A

Versions

48
Q

This is a binocular movement wher ethe visual axis of both eyes are in the same direction to maintain fixation with both eyes. Both eyes move in the same direction, by the same amount

A

Conjugate eye movements

49
Q

Disconjugate eye movement where the eyes (visual axes) rotate in the opposite directions

A

Vergences

50
Q

Both eyes rotate in to maintain binocular fixation, for instance, when reading

A

Convergence

51
Q

Both eyes roatate out

A

Divergence

52
Q

Rotation of superior portion of both eyes in

A

Incyclovergence

53
Q

Rotation of superior portion of both eyes out

A

Excyclovergence

54
Q

What is important for fusion

A

Vergences

Motility Block 9 (5 decks)

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