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Motility Block 9 > EOMs > Flashcards

EOMs Flashcards

(86 cards)

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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
What is the order of rectus muscles in order from being closest to farthest from the limbus
medial rectus Inferior rectus Lateral rectus Superior rectus
26
In primary gaze, what axis do the horizontal rectus muscles muscles move around
Z
27
Where do the horizontal and the vertical rectus muscles insert
In front of the equator
28
What axis do the vertical rectus muscles move around
X
29
Where do all EOMs arris from
The annulus of zinn
30
Moves the eye to the nose (ADDuction)
Medial rectus
31
What nerve innervates medial rectus
CN3
32
Where does medial rectus insert from the nasal limbus
5.5mm
33
How does the medial rectus course
Along the medial orbital wall
34
Why is the medial rectus prone to injury during surgery or after trauma
Because it is close to the ethmoid sinus
35
Moves the eye away from the nose (ABducts)
Lateral rectus
36
What innverates lateral rectus
CN 6
37
Where does the lateral rectus insert from the temporal limbus
6.9MM
38
How does the lateral rectus course
Along the lateral orbital wall
39
The medial and lateral orbital walls are ______ of each other
45 degrees
40
How many degrees is the orbital axis from the two orbital walls
23 degrees
41
The ______ is from the apex of the orbit to the opening of the orbit
Orbital axis
42
In primary gaze, the orbital axis is at ____ of the visual axis
23 degrees
43
Angle of the vertical recti in the orbit
Vertical recti muscles run with the orbital axis, 23 degrees of visual axis
44
Primary action is to move the eye up (elevation)
Superior rectus
45
Secondary action of the superior rectus
intorsion
46
Tertiary action of the superior rectus
Adduction
47
What innervates the superior rectus
CN 3
48
Where does the superior rectus insert relative to the superior limbus
7.7mm
49
How does the superior rectus course
Anteriorly and upward over the eyeball and laterally forming a 23 degree angle with the visual axis
50
When do the visual and orbital axes coincide
When the globe is abducted 23 degrees
51
What's the best postion to evaluate the function of the superior rectus
When the globe is abducted 23 degrees. At this point, the superior rectus acts ONLY as an elevator
52
What what point does the superior rectus act only as an elevator
When the globe is abducted 23 degrees
53
When does the superior rectus act only as an intortor?
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
Primary action is the move the eye down (depression)
Inferior rectus
55
Secondary action of inferior rectus
Extortion
56
Tertiary action of the inferior rectus
ADDuction
57
What is the inferior rectus innervated by
CN 3
58
Where does the inferior rectus insert relative to the inferior limbus
6.5mm
59
How does the inferior rectus course
Inferior and downward and laterally along the floor of the orbit forming a 23 degree angle with the visual axis
60
What position does the inferior rectus act only as a depressor?
When the globe is abducted 23 degrees
61
What is the best position to evaluate the function of the inferior rectus
When the globe is abducted 23 degrees
62
When does the inferior rectus act only as an intorter?
When the globe is aDDucted 67 degrees. Not the best way to test this
63
Those positions where there are yoked muscles/one muscle is responsible for movement
Cardinal positions
64
Primary action os superior oblique
Intortion
65
Secondary action of superior oblique
Depression
66
Tertiary action of superior oblique
Abduction
67
Superior oblique innervated by
CN 4
68
How does the superior oblique pass
Through the trochlea found between the superior and medial walls, reflects backwards and inserts in the posterior quadrant of the globe
69
Where does the superior oblique originate
From the orbital apex above the annulus of zinn, passes superiorly and upward along the superiomedial wall
70
Where doesthe superior oblique become tendinous
As it passes through the trochlea at the superior nasal aspect of the orbit
71
How does the superior oblique get redirected as it passes through the trochlea
Inferiorly, posteriorly, and laterally forming a 51 degree angle with the visual axis
72
Where does the superior oblique insert
Posteiror to the equator in the superotemporal quadrant of the eye
73
Primary action of the inferior oblique
Extortion
74
Secondary action of the inferior oblique
Elevation
75
Tertiary action of the inferior oblique
Abduction
76
What is the inferior oblique innervated by
CN 3
77
How does the inferior oblique originate
At a small depression at orbital floor
78
Where does the inferior oblique insert
In posterior lower temporal quadrant of the globe close to the macula
79
How does the inferior oblique course
Inferiorly under the inferior rectus muscle
80
What kind of angle does the inferior oblique form with the visual axis
51 degree angle
81
In terms of angles, what is the best way to test an EOM
Line it up on the angle it is relative to the visual axis
82
At what angle does the superior oblique act only as an intorter?
When the globe is abducted 39 degrees, making the visual axis and the superior oblique at 90 degrees from each other
83
At what angle does the superior oblique act as a total depressor
When aDDucted 51 degrees
84
At what angle does the inferior oblique act only as an extorter?
When the globe is abducted 39 degrees, making the angle between the visual axis and the inferior oblique 90 degrees from each other.
85
At what angle does the inferior oblique act only as an elevator?
When aDDucted 51 degrees
86
When you tell a patient to look up and to the nose (OD), and they cant, what muscle is not working?
IO

Motility Block 9 (5 decks)

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