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Extraocular Muscles Flashcards

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1
Q

What are the extraocular muscles (EOMs)?

A

Muscles that control eye movements

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2
Q

What is the primary function of the extraocular muscles?

A

To facilitate eye movements

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3
Q

Define duction

A

Monocular movement

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4
Q

Define version

A

Binocular, simultaneous, conjugate eye movements

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5
Q

Define vergence

A

Binocular, simultaneous, disjugate eye movements

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6
Q

What is the axis of the eyeball relative to the axis of the orbit?

A

23 degrees

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7
Q

List the four rectus muscles

A
  • Medial Rectus
  • Lateral Rectus
  • Superior Rectus
  • Inferior Rectus
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8
Q

What is the origin of the Medial Rectus muscle?

A

Medial portion of the common tendinous ring

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9
Q

What is the insertion point of the Medial Rectus muscle?

A

5.5 mm from the limbus

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10
Q

Which nerve innervates the Medial Rectus muscle?

A

Inferior division of the oculomotor nerve (III)

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11
Q

What action does the Medial Rectus muscle perform?

A

Adduction

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12
Q

What is the origin of the Lateral Rectus muscle?

A

Lateral portion of the common tendinous ring

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13
Q

What is the insertion point of the Lateral Rectus muscle?

A

6.9 mm from the limbus

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14
Q

Which nerve innervates the Lateral Rectus muscle?

A

Abducens nerve (VI)

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15
Q

What action does the Lateral Rectus muscle perform?

A

Abduction

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16
Q

What is the origin of the Superior Rectus muscle?

A

Tendinous ring, attached to dural sheath of the optic nerve

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17
Q

What is the insertion point of the Superior Rectus muscle?

A

7.7 mm posterior to the limbus

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18
Q

Which nerve innervates the Superior Rectus muscle?

A

Superior division of oculomotor nerve (III)

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19
Q

List the actions of the Superior Rectus muscle

A
  • Elevates the eye
  • Intorts the eye
  • Adducts the eye
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20
Q

What is the origin of the Inferior Rectus muscle?

A

Tendinous ring

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21
Q

What is the insertion point of the Inferior Rectus muscle?

A

6.5 mm from the limbus

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22
Q

Which nerve innervates the Inferior Rectus muscle?

A

Inferior division of oculomotor nerve (III)

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23
Q

List the actions of the Inferior Rectus muscle

A
  • Depresses the eye
  • Extorts the eye
  • Adducts the eye
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24
Q

What is the origin of the Superior Oblique muscle?

A

Body of sphenoid bone above and medial to the optic canal

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25
What is the insertion point of the Superior Oblique muscle?
Sclera posterior to the equator of the eyeball
26
Which nerve innervates the Superior Oblique muscle?
Trochlear nerve (IV)
27
List the actions of the Superior Oblique muscle
* Intorts the eye * Depresses the eye in adduction * Abducts the eye
28
What is the origin of the Inferior Oblique muscle?
Anterior orbital floor – orbital surface of maxilla
29
What is the insertion point of the Inferior Oblique muscle?
Into sclera underneath the lateral rectus
30
Which nerve innervates the Inferior Oblique muscle?
Inferior division of oculomotor nerve (III)
31
List the actions of the Inferior Oblique muscle
* Extorts the eye * Elevates the eye in adduction * Abducts the eye
32
What is Sherrington’s law?
Increased innervation to an extraocular muscle is accompanied by a reciprocal decrease in innervation in its antagonist
33
What is Hering’s law?
During a conjugate eye movement, yoke pairs of muscles receive equal and simultaneous innervation
34
What is the oculo-cardiac reflex?
Bradycardia precipitated by pressure on orbital contents or extraocular muscles
35
What is the Parks-Bielschowsky three-step test used for?
To diagnose cyclovertical muscle palsies
36
What are agonist-antagonist pairs?
Pairs of muscles in the same eye that move the eye in opposite directions
37
What are synergistic muscles?
Muscles in the same eye that move the eye in the same direction of gaze
38
What are yoke muscles?
Pairs of muscles in opposite eyes that work together to allow simultaneous, conjugate gaze
39
Fill in the blank: The axis of the orbit is offset _____ degrees from the axis of the eyeball.
23
40
Fill in the blank: The rectus muscles originate from the _____ tendinous ring.
common
41
Fill in the blank: The Spiral of _____ connects the insertions of the recti.
Tillaux
42
Fill in the blank: Medial rectus inserts closest to the limbus (_____ mm).
5.5
43
Fill in the blank: The medial rectus is supplied by the _____ division of the oculomotor nerve.
inferior
44
Fill in the blank: The lateral rectus is supplied by the _____ nerve.
abducens
45
Fill in the blank: Superior rectus intorts the eye and turns it 'up and in'; innervated by _____ branch of CN III.
superior
46
Fill in the blank: Inferior rectus _____ the eye and turns it 'down and in'; innervated by _____ branch of CN III.
depresses
47
Fill in the blank: Superior oblique _____ the eye and turns it 'down and out'; innervated by _____ nerve CN IV.
depresses
48
Fill in the blank: Inferior oblique extorts the eye and turns it 'up and out', innervated by _____ branch of CN III.
inferior
49
What do pairs refer to in the context of eye muscles?
Muscles in different eyes that work together in a direction of gaze.
50
What does Sherrington's law of reciprocal innervation state?
The reciprocal decreased innervation of a muscle’s antagonist.
51
What does Haring's law refer to?
The equal innervation of yoke muscle pairs.
52
What is the origin of the Superior Rectus muscle?
CTR.
53
What is the insertion point of the Superior Rectus muscle?
7.7mm from limbus.
54
Which cranial nerve innervates the Superior Rectus muscle?
CN III – Sup. division.
55
What are the actions of the Superior Rectus muscle?
* Elevates * Intorts * Adducts
56
What is the origin of the Inferior Rectus muscle?
CTR.
57
What is the insertion point of the Inferior Rectus muscle?
6.5mm from limbus.
58
Which cranial nerve innervates the Inferior Rectus muscle?
CN III – Inf. division.
59
What are the actions of the Inferior Rectus muscle?
* Depresses * Extorts * Adducts
60
What is the origin of the Lateral Rectus muscle?
CTR (2 heads).
61
What is the insertion point of the Lateral Rectus muscle?
6.9mm from limbus.
62
Which cranial nerve innervates the Lateral Rectus muscle?
CN VI.
63
What is the action of the Lateral Rectus muscle?
Abducts.
64
What is the origin of the Medial Rectus muscle?
CTR.
65
What is the insertion point of the Medial Rectus muscle?
5.5mm from limbus.
66
Which cranial nerve innervates the Medial Rectus muscle?
CN III – Inf. division.
67
What is the action of the Medial Rectus muscle?
Adducts.
68
What is the origin of the Superior Oblique muscle?
Body of Sphenoid bone.
69
Where does the Superior Oblique muscle insert?
Inserts into the sclera posteriorly to the equator of the eyeball.
70
Which cranial nerve innervates the Superior Oblique muscle?
CN IV.
71
What are the actions of the Superior Oblique muscle?
* Intorts * Depresses * Abducts
72
What is the origin of the Inferior Oblique muscle?
Anterior orbital floor (maxilla).
73
Where does the Inferior Oblique muscle insert?
Inserts into the sclera under the lateral rectus.
74
Which cranial nerve innervates the Inferior Oblique muscle?
CN III – Inf. division.
75
What are the actions of the Inferior Oblique muscle?
* Extorts * Elevates * Abducts
76
What is the topic of the debate mentioned in the content?
Does structure determine function, or does function determine structure?
77
What is suggested to be drawn on the board?
The Spiral of Tillaux.

Ocular Anatomy (12 decks)

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