Eye muscles - Extrinsic Flashcards

1
Q

What set of muscles function is to move the eyeball

A

Extrinsic muscles

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2
Q

What is the two groups of extrinsic eye musles

A

4 sets of Recti Muscles

  • Superior
  • Inferior
  • Medial
  • Lateral

2 sets of Oblique Muscles

  • Superior
  • Inferior
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3
Q

What is an added exception to the extrinsic muscles

A

Levator palebare superiors

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4
Q

Where do the recti muscles arise from

A

Arise from the apex of the orbit from an annular fibrosis ring

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5
Q

What is the only extrinsic muscle that arises anteriorly

A

Inferior oblique - arises from the roof of the orbit anteriorly

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6
Q

Where does the superior oblique arise from

A

arise from the roof of the orbit posteriorly

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7
Q

What alternates the direction of the superior oblique

A

Trochlear turns the muscle back to the sclera

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8
Q

Where is the location of the levator palpebral superiors

A

Sits onto of the superior recti and innervates the upper eye lid

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9
Q

What is the function of the levator palpebral superiors

A

Elevates upper eye lid

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10
Q

What is the 6 binocular movements of the eye

A
Dextroelevation – up to right 
Levo-elevation – up and to the left 
Dextroversion – to the right 
Levo-version – to the left 
Dextro depression – down to right 
Levo depression – down to left
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11
Q

What is the unicular movements of the eye

A

Away from nose = adduction

Towards nose = abduction

Elevation

Depression

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12
Q

What two movements allow the image to remain straight when you tilt your head

A

Intorsion and extorsion

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13
Q

Define intorsion

A

top of eye ball moves and rotates to nose

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14
Q

Define extorsion

A

top of eye ball rotates away from nose

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15
Q

What does the opposing eye do if one eye intorts

A

Extrorts

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16
Q

What is the disadvantage of humans having more frontal binocular vision

A

Decreased visual field

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17
Q

What is the advantage of humans having more frontal binocular vision

A

Gives the ability of depth perception

two eyes see sought different image on the same object, therefore have a better understanding of how far way it is

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18
Q

What is the position of the eye in the orbit

A

Eyeballs angle outwards in orbit (but still look straight ahead)

19
Q

How are the extrinsic muscles attached to the eye ball

A

The extrinsic muscles are attaches along the orbital axis

20
Q

What is the implication of the muscles attaching to the orbital axis rather than the occipital axis mean

A

Most muscles have more than one action

21
Q

What is the implication of the oblique muscles attaching posteriorly

A

so they pull posterior part of the eye ball up/down and the anterior part moves in the opposite direction

22
Q

What muscle attachments are in the horizontal plane and what implication does this have on eye movement

A

Medial and lateral recti muscles

Simple movements:

Medial contact - adducts

Lateral contract - abducts

23
Q

What allows the Inferior and superior recti to perform primary actions of elevation and depression

A

When the muscles become parallel to optical axis

24
Q

What movements put the Superior and Inferior recti parallel to the occipital axis

A

When the Lateral recti abduct the eye

25
What allows the superior recti to intort and the inferior recti to extort
When the medial recti adducts the eye placing the superior and inferior recti muscle perpendicular to occipital axis
26
What is the primary function of the Oblique muscles
SO - Rotation inwards IO- Rotation outwards
27
What is the secondary function of the Superior and inferior oblique muscles
SO - depression | IO- elevation
28
What causes the superior oblique to intort
When eyeball is abducted
29
What causes the inferior oblique to extort
When the eyeball is abducted
30
When can the obliques elevate or depress the eye
when the eye is adducted
31
When can the superior and inferior rect elevate or depress the eye
when the eye is abducted
32
What is the 3 primary actions of the Superior recti
1. Elevation 2. Adduction 3. intorsion
33
What is the 3 primary actions of the inferior recti
1. Depression 2. Adduction 3. Extortion
34
What is the 3 primary actions of the inferior oblique
1. Extorsion 2. Elevation 3. Abduction
35
What is the 3 primary actions of the Superior oblique
1. Intorsion 2. Depression 3. Abduction
36
Define strabismus
Misalignment of the eyes (squint)
37
What is esotropia strabismus
Convergent squint
38
What is exotropia strabismus
Divergent squint
39
What is the two functional consequences of a squint
Amblyopia | Diplopia
40
Define amblyopia
= lazy eye | Where brain supresses the image of one eye leading to poor vision in that eye without any pathology
41
How and when is amblyopia best correctable
correctable in early years using eye patches to stimulate the “lazy” eye to work
42
define diplopia
double vision
43
When does diplopia usually occur in squints
due to nerve palsies