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The Nervous System: The eye > Eye muscles - Extrinsic > Flashcards

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
Q

What allows the superior recti to intort and the inferior recti to extort

A

When the medial recti adducts the eye placing the superior and inferior recti muscle perpendicular to occipital axis

26
Q

What is the primary function of the Oblique muscles

A

SO - Rotation inwards IO- Rotation outwards

27
Q

What is the secondary function of the Superior and inferior oblique muscles

A

SO - depression

IO- elevation

28
Q

What causes the superior oblique to intort

A

When eyeball is abducted

29
Q

What causes the inferior oblique to extort

A

When the eyeball is abducted

30
Q

When can the obliques elevate or depress the eye

A

when the eye is adducted

31
Q

When can the superior and inferior rect elevate or depress the eye

A

when the eye is abducted

32
Q

What is the 3 primary actions of the Superior recti

A
  1. Elevation
  2. Adduction
  3. intorsion
33
Q

What is the 3 primary actions of the inferior recti

A
  1. Depression
  2. Adduction
  3. Extortion
34
Q

What is the 3 primary actions of the inferior oblique

A
  1. Extorsion
  2. Elevation
  3. Abduction
35
Q

What is the 3 primary actions of the Superior oblique

A
  1. Intorsion
  2. Depression
  3. Abduction
36
Q

Define strabismus

A

Misalignment of the eyes (squint)

37
Q

What is esotropia strabismus

A

Convergent squint

38
Q

What is exotropia strabismus

A

Divergent squint

39
Q

What is the two functional consequences of a squint

A

Amblyopia

Diplopia

40
Q

Define amblyopia

A

= lazy eye

Where brain supresses the image of one eye leading to poor vision in that eye without any pathology

41
Q

How and when is amblyopia best correctable

A

correctable in early years using eye patches to stimulate the “lazy” eye to work

42
Q

define diplopia

A

double vision

43
Q

When does diplopia usually occur in squints

A

due to nerve palsies

The Nervous System: The eye (11 decks)

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