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Ocular Motility > Kinematics > Flashcards

Kinematics Flashcards

1
Q

Define

  1. Origin
  2. Insertion
  3. Muscle cone
A
  1. Origin is where the muscle attaches to the bony orbit
  2. Insertion is where the muscle attaches to the globe
  3. Formed by the recti muscles. Origin at the annulus of zinn.
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2
Q

Kinematics is

A

The branch of classical mechanics that describes the motion of points, bodies, and systems of bodies without consideration of the forces that cause it.

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3
Q

Optic Neuritis

A

Inflammation of the optic nerve. Pain on EOMs may be an early sign. Could also present as an APD.

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4
Q

Spiral of Tilleaux.

A

Trend of how far the recti muscles insert from the limbus

Medial rectus has the most anterior insertion and the SR has the most posterior insertion.

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5
Q

The SR has a connected sheath with

A

The levator muscle. Coordinated eye movements with eyelids.

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6
Q

Angle of attachment for the SR and IR

A

23 degree from the Y axis (Ficks. Line of sight)

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7
Q

The IR Is exactly parallel with which other muscle?

A

The SR, which is important for coordinated movements. They should always match each other.

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8
Q

The IR passes above or below the IO?

A

Above

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9
Q

Lateral rectus origin

A

Upper and lower limb of the annulus of zinn and the process of the greater wing of the sphenoid.

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10
Q

Role of the lateral and medial check ligaments

A

They are both fascicle expansions of the muscle sheathes from the medial and lateral recti muscles. The check ligaments prevent eye from rotating into orbit.

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11
Q

Attachment of lateral rectus at lateral wall of orbit

A

Whitnall’s Tubercle

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12
Q

Origin of the medial rectus

A

Upper and lower annulus of zinn along with the ON stealth. Would result in pain with ON inflammation.

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13
Q

SO is at which angle to the Y axis

A

54 degrees

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14
Q

Anatomical origin of the SO

Physiological origin

A

Lesser wing of the sphenoid
Catilaginous trochlea on the superior medial orbit wall.
The muscle ends before the trochlea. The tendon passes through the trochlea.

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15
Q

Insertion of the SO

A

Lateral posterior globe. Behind equator of the globe, which is important for the function.

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16
Q

Superior oblique primary, secondary, and tertiary functions

A

Intorsion, abduction, and depression.

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17
Q

Origin of the IO

A

Maxillary bone inferior to nasolacrimal fossa

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18
Q

Insertion of the IO

A

Posterior lateral globe. Mostly inferior.

19
Q

The IO has what degree angle with the visual axis/Y axis?

A

51

20
Q

Tangential point

A

Where the center of the muscle or tendon first touches the globe. Tangent here indicates the direction of pull.
Tangential point can move. Changes when the muscle contracts or relaxes

21
Q

Arc of contact

A

The arc formed between the tangential point and the center of the insertion on the sclera. Varies in length as the muscle contracts.

22
Q

Muscle plane

A

Determined by a tangential point and the center of rotation. Describes direction of pull of the muscle. Determines the axis of rotation.

23
Q

Axis of rotation is determined by

A

The muscle plane, which is determined by the tangential point.

The axis of rotation is that around which the muscle would rotate if contracting in isolation.

24
Q

Strabismus Surgery. Resection.

A

A section cut out (not including the point of insertion) to make a shorter muscle/stronger pull.

MR for exotrope and LR for esotrope

25
Q

Strabismus surgery. Recession.

A

Receed. Longer muscle. Weaker pull. Doesn’t mess with the already formed origin of insertion, but also creates a new one further back and hopes the old origin doesn’t cause any issues.

Decreases effective pull.

MR for esotrope
LR for exotrope

26
Q

Strabismus surgery. Transposition.

A

Moves the LR and MR up or down on the globe to effectively change the line of sight for vertical deviations.

Difficult to access SR and IR since they share fascicle sheathes, which is why vertical deviations are often treated this way.

27
Q

Field of fixation

A

Area within which central fixation is possible by moving only the eyes.

Mapping out where fovea is able to come in contact with a line of sight. Ask pt to move eyes monocularly and binocularly around as much as possible.

Monocular fields of fixation are larger than binocular since for binocular, both foveas have to be focusing on the same point at the same time.

28
Q

Limits to field of fixation

A

Configuration of structures around the eye- check ligament and nose
Refraction of the globe- long vs short axis.

Decrease will occur with age.

29
Q

PRACTICAL field of fixation

A

Includes head movements and is much larger.

30
Q

Primary, secondary, and tertiary POSITION

A

primary gaze: lines of sight are horizontal and perpendicular to the line between their centers of rotation.

Secondary gaze: Assumed when the eye moves from primary position along the horizontal or vertical axis. (up, down, left, or right).

Tertiary position: Assumed when the eye moves to any other location.

31
Q

Muscle plane is determined by what?

A

determined by a tangential point and the center of rotation.

32
Q

How does the tangential point and the muscle plane influence direction of pull?

A

Tangential point INDICATES direction of pull.

Muscle plane DESCRIBES direction of pull.

33
Q

The muscle plane determines the

A

Determines the axis of rotation. That around which the muscle would rotate if contracting in isolation. Axis of rotation is in the center of the muscle plane.

So if the muscle plane moves due to tangential point or center of rotation, it will cause the axis of rotation to also change.

34
Q

Tangential point determines ___

Muscle plane determines __

A

Tangential point determines direction of pull.

Muscle plane determines axis of rotation- that around which the muscle would rotate if contracting in isolation.

35
Q

When eyes are in primary gaze, what 3 angles are made?

A

23 degree angle made at line of sight due to superior and inferior rectus.

45 degree angle made at apex of orbit.

90 degree angle made near pituitary gland.

36
Q

Protrustion

A

Anterior, out of orbit

37
Q

Retraction

A

Posterior, into orbit

38
Q

OU Extort

A

Excyclovergence

39
Q

OU intort

A

Incyclovergence

40
Q

OU adduct

A

Convergence

41
Q

OU abcuct

A

Divergence

42
Q

OU right rotation

A

Dextrocycloversion

43
Q

OU left rotation

A

Levocycloversion

Ocular Motility (8 decks)

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