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Motility Block 9 > EOMs > Flashcards

EOMs Flashcards

1
Q

What is the action of a muscle due to

A

The direction of its pull around the axes

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2
Q

This is a muscles major effect on the postion of the eye when the muscle contracts while the head is in the primary postion

A

Primary action

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3
Q

These are the additional effect a muscle has on the position of the eye

A

Secondary and tertiary action

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4
Q

How far can the eyes move before the head moves

A

Move about 50 degrees, but at about 20, the head turns

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5
Q

Point at the center of the muscle or tendon that first touches the globe

A

Tangential point

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6
Q

This the arc formed between the tangential point and the center of insertion of the muscle on the sclera. It changes in length as a muscle contracts.

A

Arc of contact

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7
Q

When is arc of contact longer

A

When a muscle is relaxed

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8
Q

When is the arc of contact shorter

A

When a muscle interacts

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9
Q

Describes the direction of pull of the muscle and determines the axis the muscle will move around

A

Muscle plane

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10
Q

The visual axis passes from the ______ to the _______

A

Fovea to the point of fixation

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11
Q

The visual axis from both eyes in normal binocular single vision

A

Intersects at fixation

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12
Q

An imaginary coronal plane through the center of the globe

A

Listing plane

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13
Q

The globe rotates on the ______

A

Axes of fick

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14
Q

The eye rotates vertically (up and down) on this axis

A

X

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15
Q

The eye makes torsional rotations like a wheel around this axis. This axis is similar to the anatomical axis of the eye. The top of the eye rotates clockwise or counter clockwise

A

Y

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16
Q

The eye rotates horizontally (left and right) on this axis

A

Z

Zide to zide

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17
Q

How many EOMs

A

6

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18
Q

How many rectus muscles

A

4

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19
Q

How many oblique muscles

A

2

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20
Q

Rectus muscles

A

Superior
Inferior
Medial
Lateral

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21
Q

Oblique muscles

A

Superior

Inferior

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22
Q

The imaginary line joining the insertions of the 4 rectus muscles

A

Spiral of Tillaux

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23
Q

What is an important reference for surgery when it comes to EOMs

A

Spiral of tillaux

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24
Q

How is the spiral of Tillaux situated

A

Starting at the medial rectus, each rectus muscle is located further away from the limbus

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25
Q

What is the order of rectus muscles in order from being closest to farthest from the limbus

A

medial rectus
Inferior rectus
Lateral rectus
Superior rectus

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26
Q

In primary gaze, what axis do the horizontal rectus muscles muscles move around

A

Z

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27
Q

Where do the horizontal and the vertical rectus muscles insert

A

In front of the equator

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28
Q

What axis do the vertical rectus muscles move around

A

X

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29
Q

Where do all EOMs arris from

A

The annulus of zinn

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30
Q

Moves the eye to the nose (ADDuction)

A

Medial rectus

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31
Q

What nerve innervates medial rectus

A

CN3

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32
Q

Where does medial rectus insert from the nasal limbus

A

5.5mm

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33
Q

How does the medial rectus course

A

Along the medial orbital wall

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34
Q

Why is the medial rectus prone to injury during surgery or after trauma

A

Because it is close to the ethmoid sinus

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35
Q

Moves the eye away from the nose (ABducts)

A

Lateral rectus

36
Q

What innverates lateral rectus

A

CN 6

37
Q

Where does the lateral rectus insert from the temporal limbus

A

6.9MM

38
Q

How does the lateral rectus course

A

Along the lateral orbital wall

39
Q

The medial and lateral orbital walls are ______ of each other

A

45 degrees

40
Q

How many degrees is the orbital axis from the two orbital walls

A

23 degrees

41
Q

The ______ is from the apex of the orbit to the opening of the orbit

A

Orbital axis

42
Q

In primary gaze, the orbital axis is at ____ of the visual axis

A

23 degrees

43
Q

Angle of the vertical recti in the orbit

A

Vertical recti muscles run with the orbital axis, 23 degrees of visual axis

44
Q

Primary action is to move the eye up (elevation)

A

Superior rectus

45
Q

Secondary action of the superior rectus

A

intorsion

46
Q

Tertiary action of the superior rectus

A

Adduction

47
Q

What innervates the superior rectus

A

CN 3

48
Q

Where does the superior rectus insert relative to the superior limbus

A

7.7mm

49
Q

How does the superior rectus course

A

Anteriorly and upward over the eyeball and laterally forming a 23 degree angle with the visual axis

50
Q

When do the visual and orbital axes coincide

A

When the globe is abducted 23 degrees

51
Q

What’s the best postion to evaluate the function of the superior rectus

A

When the globe is abducted 23 degrees. At this point, the superior rectus acts ONLY as an elevator

52
Q

What what point does the superior rectus act only as an elevator

A

When the globe is abducted 23 degrees

53
Q

When does the superior rectus act only as an intortor?

A

When the globe is aDDucted 67 degrees, making the angle between the visual and orbital axes 90 degrees.
Not the best way to evaluate the superior rectus

54
Q

Primary action is the move the eye down (depression)

A

Inferior rectus

55
Q

Secondary action of inferior rectus

A

Extortion

56
Q

Tertiary action of the inferior rectus

A

ADDuction

57
Q

What is the inferior rectus innervated by

A

CN 3

58
Q

Where does the inferior rectus insert relative to the inferior limbus

A

6.5mm

59
Q

How does the inferior rectus course

A

Inferior and downward and laterally along the floor of the orbit forming a 23 degree angle with the visual axis

60
Q

What position does the inferior rectus act only as a depressor?

A

When the globe is abducted 23 degrees

61
Q

What is the best position to evaluate the function of the inferior rectus

A

When the globe is abducted 23 degrees

62
Q

When does the inferior rectus act only as an intorter?

A

When the globe is aDDucted 67 degrees. Not the best way to test this

63
Q

Those positions where there are yoked muscles/one muscle is responsible for movement

A

Cardinal positions

64
Q

Primary action os superior oblique

A

Intortion

65
Q

Secondary action of superior oblique

A

Depression

66
Q

Tertiary action of superior oblique

A

Abduction

67
Q

Superior oblique innervated by

A

CN 4

68
Q

How does the superior oblique pass

A

Through the trochlea found between the superior and medial walls, reflects backwards and inserts in the posterior quadrant of the globe

69
Q

Where does the superior oblique originate

A

From the orbital apex above the annulus of zinn, passes superiorly and upward along the superiomedial wall

70
Q

Where doesthe superior oblique become tendinous

A

As it passes through the trochlea at the superior nasal aspect of the orbit

71
Q

How does the superior oblique get redirected as it passes through the trochlea

A

Inferiorly, posteriorly, and laterally forming a 51 degree angle with the visual axis

72
Q

Where does the superior oblique insert

A

Posteiror to the equator in the superotemporal quadrant of the eye

73
Q

Primary action of the inferior oblique

A

Extortion

74
Q

Secondary action of the inferior oblique

A

Elevation

75
Q

Tertiary action of the inferior oblique

A

Abduction

76
Q

What is the inferior oblique innervated by

A

CN 3

77
Q

How does the inferior oblique originate

A

At a small depression at orbital floor

78
Q

Where does the inferior oblique insert

A

In posterior lower temporal quadrant of the globe close to the macula

79
Q

How does the inferior oblique course

A

Inferiorly under the inferior rectus muscle

80
Q

What kind of angle does the inferior oblique form with the visual axis

A

51 degree angle

81
Q

In terms of angles, what is the best way to test an EOM

A

Line it up on the angle it is relative to the visual axis

82
Q

At what angle does the superior oblique act only as an intorter?

A

When the globe is abducted 39 degrees, making the visual axis and the superior oblique at 90 degrees from each other

83
Q

At what angle does the superior oblique act as a total depressor

A

When aDDucted 51 degrees

84
Q

At what angle does the inferior oblique act only as an extorter?

A

When the globe is abducted 39 degrees, making the angle between the visual axis and the inferior oblique 90 degrees from each other.

85
Q

At what angle does the inferior oblique act only as an elevator?

A

When aDDucted 51 degrees

86
Q

When you tell a patient to look up and to the nose (OD), and they cant, what muscle is not working?

A

IO

Motility Block 9 (5 decks)

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