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Binocular vision > EOMs:introduction to eye movements & dynamics of extra-ocular muscle actions > Flashcards

EOMs:introduction to eye movements & dynamics of extra-ocular muscle actions Flashcards

1
Q

what do all of the 6 EOMs work to produce

A

ocular movement around the centre of rotation

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2
Q

what is the name of the EOM which is not apart of the other 6 EOMs

A

levator palpebrae superioris (LPS)

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3
Q

which EOMs does the 3rd CN oculomotor superior division innervate

A
  • SUPERIOR rectus

- levator palpebrase SUPERIORIS

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4
Q

which EOMs does the 3rd CN oculomotor inferior division innervate

A
  • medial rectus
  • INFERIOR rectus
  • INFERIOR oblique
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5
Q

which EOM does the 4th CN trochlear innervate

A

superior oblique (i.e. the name of its pulley is called trochlear)

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6
Q

which EOM does the 6th CN abducens innervate

A

lateral rectus (ie abducts the eye)

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7
Q

where is the anatomical origin of the 4 recti muscles

A

at the annulus of zinn

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8
Q

what does the mechanical origin of an EOM define

A

where the pull comes from e.g. for recti muscles it comes from behind

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9
Q

where are the muscle pulleys of the 4 recti located

A

10mm posterior to equator of globe

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10
Q

where are all 4 recti muscles inserted in the globe

A

anterior/in front of the equator

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11
Q

which direction does the cornea rotate when each 4 recti muscle contracts

A

cornea rotates towards the body of the muscle itself

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12
Q

what is the primary action of the medial rectus

A

inwards

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13
Q

what is the primary action of the lateral rectus

A

outwards

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14
Q

what is the primary action of the superior rectus

A

upwards

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15
Q

what is the primary action of the inferior rectus

A

downwards

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16
Q

where is the anatomical origin of the superior oblique EOM

A

annulus of zinn

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17
Q

where is the anatomical origin of the inferior oblique

A

anterior infero-nasal corner

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18
Q

what is the pulley of the superior oblique called

A

trochlear

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19
Q

where is the trochlear (pulley) of the superior oblique located i.e. where does it pull from (mechanical origin)

A

anterior supero-nasal corner or orbital rim

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20
Q

where does the inferior oblique pull from (mechanical origin)

A
  • anterior & inferior to globe

- coupled to inferior rectus muscle

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21
Q

so where are the mechanical origins of both obliques located

A

anterior to the globe (as oppose to recti which are all posterior to globe)

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22
Q

where are both oblique EOMs inserted in the globe

A

behind the equator

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23
Q

as each oblique muscle contracts, where does the cornea rotate

A

away from the body of the muscle itself

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24
Q

what is the action of the superior oblique

A

downwards

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25
Q

what is the action of the inferior oblique

A

upwards

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26
Q

what type of arc around the limbus do the recti muscles form from their insertions

A

concave arc

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27
Q

how are the MR & IR insertions in relation to the limbus

A

concentric (follows the contour of the limbus adjacently)

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28
Q

how are the SR & IR insertions in relation to the limbus

A
  • tilted slightly nasally

- closest to limbus on nasal side

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29
Q

what type of arc around the limbus to the oblique muscles form, from their insertions

A
  • convex arc

- insertions fan out

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30
Q

how far behind the limbus is the MR inserted

A

5.5mm closest to limbus

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31
Q

how far behind the limbus is the IR inserted

A

6.5mm

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32
Q

how far behind the limbus is the LR inserted

A

7.0mm

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33
Q

how far behind the limbus is the SR inserted

A

7.5mm farthest from the limbus

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34
Q

which recti muscle does the IO muscle insertion lie under

A

lateral rectus

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35
Q

what does the posterior end of the IO overlie the position of

A

the fovea

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36
Q

which recti muscle does the SO muscle insertion lie under

A

superior rectus

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37
Q

in the primary position, where is the centre of rotation located

A

13.5mm behind the apex of the cornea

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38
Q

list the three axis of rotation of fick’s axis

A

z axis
x axis
y axis

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39
Q

which direction does the z axis run

A

vertically through the eye

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40
Q

which direction does the z axis allow us to look

A

horizontally

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41
Q

which EOMs look horizontally around the z axis

A

medial rectus & lateral rectus

Adduction and abduction

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42
Q

which direction does the x axis run

A

horizontally through the eye

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43
Q

which direction does the x axis allow us to look

A

vertically

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44
Q

which EOMs look vertically around the x axis

A 
superior rectus 
inferior rectus 
inferior oblique 
superior oblique 
elevation and depression
45
Q

which direction does the y axis run

A

obliquely through the eye (through the cornea)

46
Q

which direction does the y axis allow us to run

A

cyclo rotation or torsionally

47
Q

which EOMs look torsionally around the y axis

A

inferior oblique
superior oblique
superior rectus
inferior rectus

48
Q

what is rotation of only ONE single eye termed

A

duction i.e. other eye is covered when doing adduction on a px etc

49
Q

what are duction movements limited by

A

length of muscle + tendon, edge of orbit & soft tissue of the orbit

50
Q

what does rotation of a SINGLE eye around the z axis produce

A

horizontal movement:

  • adduction
  • abduction
51
Q

what does rotation of a SINGLE eye around the x axis produce

A

vertical movement:

  • supraduction (elevation)
  • infraduction (depression)
52
Q

what is the duction (single eye) term for elevation

A

supraduction

53
Q

what is the duction (single eye) term for depression

A

infraduction

54
Q

what does rotation of a SINGLE eye around the y axis produce

A

torsional movement:

  • excycloduction (extorsion) anti clockwise
  • incycloduction (intorsion) clockwise
55
Q

what is the duction (single eye) term for extorsion

A

excycloduction

56
Q

what is the duction (single eye) term for intorsion

A

incycloduction

57
Q

what are oblique movements a combination of

A

horizontal and vertical movements

moves the globe into various oblique positions e.g. up and to the right or down and to the left etc

58
Q

what is primary position of gaze

A

when the eyes are looking straight ahead with body and head erect

59
Q

what happens to the contraction of a muscle when that muscle axis of rotation coincides with one of fick’s axis or rotation e.g. z horizontal, x vertical or y torsional axis

A

contraction of that muscle will produce a rotation purely around that particular axis
e.g. if the lateral rectus axis of rotation coincides with the z axis, it will be purely horizontal or if it coincides with the x axis, it will be purely vertical

60
Q

what is the muscle plane

A

a point where the muscle first touches the globe (tangental point) and the centre of rotation i.e. the orientation that is inserts into the eye

61
Q

what is a muscle axis of rotation perpendicular to

A

the muscle plane (the orientation that it inserts into the eye) e.g. if a muscle inserts vertically it will only produce horizontal movements

62
Q

in primary position what does the horizontal rectus muscles axis of rotation completely coincide with of fick’s axis and hat contraction does that muscle produce as a result

A

z axis of rotation, produces a pure rotation around the vertical axis so NO vertical nor torsional component

63
Q

which EOMs have only one action which is their primary and only action

A

medial rectus - adduction

lateral rectus - abduction

64
Q

in primary position which of fick’s axis does the superior rectus coincide with

A

z ONLY, not with x or y

65
Q

in primary position what is the primary action of the superior rectus

A

elevation

66
Q

in primary position what is the secondary action of the superior rectus

A

incyloduction

67
Q

in primary position what is the tertiary action of the superior rectus

A

adduction

68
Q

what does RADSIN stand for

A

Recti
ADduct
Superiors
INtort

69
Q

which muscle does the superior rectus lie adjacent to and what does that result in when the eye elevates

A

adjacent to the levator palpebrae superioris

as eye elevates input to the LPS produces lid elevation

70
Q

what angle does the superior rectus axis of rotation form with the x axis

A

23 degrees

71
Q

what angle does the superior rectus axis of rotation from with the y axis

A

67 degrees

72
Q

what does the superior rectus axis of rotation coincide with when the globe is abducted 23 degrees

A

x axis

73
Q

when the superior rectus coincides with the x axis, what does it purely become

A

pure elevator

74
Q

what does the superior rectus axis of rotation coincide with when the globe is adducted 67 degrees

A

y axis

75
Q

when the superior rectus coincides with the y axis, what does it purely become

A

pure incycloduction

76
Q

what angle does the inferior rectus axis of rotation form with the x axis

A

23 degrees

77
Q

what angle does the inferior rectus axis of rotation form with the y axis

A

67 degrees

78
Q

in primary position what is the primary action of the inferior rectus

A

depression

79
Q

in primary position what is the secondary action of the inferior rectus

A

excycloduction

80
Q

in primary position what is the tertiary action of the inferior rectus

A

adduction

81
Q

what does RADSIN impose about recti muscles

A

recti ADDUCT

82
Q

what does RADSIN impose about superior muscles

A

superiors INTORT

83
Q

what does the inferior rectus axis of rotation coincide with when the globe is abducted 23 degrees

A

x axis

84
Q

what does the inferior rectus axis of rotation coincide with when the globe is abducted 67 degrees

A

y axis

85
Q

when the inferior rectus coincides with the x axis, what does it purely become

A

pure depressor

86
Q

when the inferior rectus coincides with the y axis, what does it purely become

A

pure excycloduction

87
Q

what angle does the superior oblique axis of rotation form with the x axis

A

54 degrees

88
Q

what angle does the superior oblique axis of rotation form with the y axis

A

36 degrees

89
Q

in primary position, what is the primary action of the superior oblique

A

incycloduction

90
Q

in primary position, what is the secondary action of the superior oblique

A

depression

91
Q

in primary position, what is the tertiary action of the superior oblique

A

abduction

92
Q

when the superior oblique coincides with the y axis i.e. abducts 36 degrees, what does it purely become

A

pure incycloduction

93
Q

when the superior oblique coincides with the x axis i.e. adducts 54 degrees, what does it purely become

A

pure depressor

94
Q

what angle does the inferior oblique axis of rotation form with the y axis

A

39 degrees

95
Q

what angle does the inferior oblique axis of rotation form with the x axis

A

51 degrees

96
Q

in the primary position, what is the primary action of the inferior oblique

A

excylcoduction

97
Q

in the primary position, what is the secondary action of the inferior oblique

A

elevation

98
Q

in primary position, what is the tertiary position of the inferior oblique

A

abduction

99
Q

which EOMs is the tertiary action of when in primary position

A

abduction

100
Q

when the inferior oblique coincides with the y axis i.e. abducts 39 degrees, what does it purely become

A

pure excycloduction

101
Q

when the inferior oblique coincides with the x axis i.e. adducts 51 degrees, what does it purely become

A

pure elevator

102
Q

which EOMs have three actions in primary position

A

SR, IR, SO & IO

103
Q

when the eye is adducted, what does the superior oblique produce

A

depression

104
Q

when the eye is adducted, what does the inferior oblique produce

A

elevation

105
Q

when the eye is abducted, what does the superior rectus produce

A

elevation

106
Q

when the eye is abducted, what does the inferior rectus produce

A

depression

107
Q

list which actions the superior oblique has in primary position

A
  • elevation
  • adduction
  • intorsion
108
Q

list which actions the inferior oblique has in primary position

A
  • elevation
  • abduction
  • extorsion

Binocular vision (12 decks)

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