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OV2018 binocular vision > Extraocular muscles 2 > Flashcards

Extraocular muscles 2 Flashcards

1
Q

What do we need to do in order to determine the strength or weakness of the eye muscle ?

A

-that we move the eye muscle in the position of gaze where it is been maximally used

as for e.g
if looking at biceps , when they are relaxed it is really hard to determine their strength or weakness but when they are tensed it is much easier too. Just like with the eye.

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2
Q

How can you determine the subtle weakness of the eye muscle even more ?

A

-the further you manage to move the eye into the position of gaze where it is maximally used

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3
Q

When looking to the right what do we say to px ?

A

dextroversion

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4
Q

When looking to the left what do we say to px?

A

laevoversion

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5
Q

When looking UP what do we ask px ?

A

elevation

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6
Q

When looking down what do we ask px ?

A

depression

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7
Q

What do you ask px when looking down into the right IN THE RIGHT EYE ?

A

dextrodepression

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8
Q

What do you ask px when looking up to the right IN THE RIGHT EYE ?

A

dextroelevation

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9
Q

What position of gaze is not good in order to determine the EOM weakness ?

A

primary gaze -

  • as the muscles are barely working at this position of gaze-we wouldnt be able to detect a subtle weakness.
  • if right eye was right and up we wouldn’t know which one was weak as all muscles are equally innervated .
  • secondly -
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10
Q

Why is direct elevation and direct depression not a good position of gaze to determine which EOM are weak?

A

because for e.g if you ask -px to look up and their right eye doesnt look up , you dont know which muscle is weak as there are 2 muscles that are working

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11
Q

How many muscles of the right eye are pulling into dextroversion ?

A

only one muscle maximally used - RLR

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12
Q

How many muscles of the left eye are pulling into dextroversion ?

A

only one muscle maximally used- LMR

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13
Q

What are good secondary positions of gaze to ask px to look at when determining a weak EOM?

A

direct dextroversion and direct laeoversion.
-this because one muscle is maximally used in each eye therefore this is where you can look for the weakness of one of the muscles if one is not working.

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14
Q

What happens if they right lateral rectus is weak in the right eye ?

A

the eye moves inwards- esotropic

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15
Q

What happens if the right medial rectus is weak in the right eye ?

A

the eye moves outwards - exotropic

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16
Q

What happens if MR is weak ?

A

MR- aDduction - the eye would become exotropic

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17
Q

What happens if LR is weak ?

A

LR- aBduction- the eye would become esotropic

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18
Q

What are the muscles that are maximally used in the tertiary positions ?

A
  • only one muscle of each eye is being maximally used

-

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19
Q

What tertiary position of gaze is useful to bring px into to determine muscle weakness ?

A

dextrodepression and laevodepression

e. g if you wanted to investigate RIR weakness - bring px into dextrodepression- as this is where the RIR is being used
e. g if wanted to see if there was a RSO weakness - bring px in laevodepression-as this is where the RSO muscle is being used.

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20
Q

What actions do each muscle have in primary position ?

A

-when their head is straight and eyes are straight
-for e.g if you asses this superior rectus muscle , and in primary position this muscle has 3 actions
1st action- elevation
in order to determine the last 2 actions (2nd=incycloduction and 3rrd = Adduction- need to see RADSIN)
-so superior rectus is a rectus muscle therefore the secondary action is going to be adduction and the final action comes from the SIN part - superior rectus is intort- so therefore is going to be incycloduction.

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21
Q

What does RADSIN stand for ?

A

R- recti (means rectus)
AD - aDduct- (action means adduction)
SIN- superior intort- ( which action means incycloduction)

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22
Q

What would happen to eye if SR was weak ?

A
  • if fail to elevate eye - means it is hypotropic
  • if the eye failed intort/incycloducted - the eye would become extorted/excycloducted.
  • if the eye failed to aDduct- - the muscle would not pull into the nose - the eye would abduct- therefore the eye will be exotropic
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23
Q

What deviation would you see in primary position if SR was weak ?

A

Deviation would be :

  • Hypotropic
  • Extorted
  • Exotropic
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24
Q

What action does the superior rectus has when it is being maximally used in the right and left eye?

A

RSR(right) and LSR(left)
RSR- is where it is maximally used in dextroelevation
LSR- is where it is maximally used in laevoelevation
-maximally used when that eye is looking away from the nose.

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25
Q

What do you ask px when looking UP into the left IN THE LEFT EYE ?

A

laevoelevation

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26
Q

What actions do the SR have when they are looking away from the nose ? angle

A

from last weeks lecture :

  • when eyes are abDucted (away from nose) by 23 degrees ,the muscle axis of rotation coincides with the x axis and the x axis always controls vertical actions therefore when eyes are abducted by 23degrees- we turn SR into a pure elevator
  • However if the SR are weak , they will be unable to elevate the eyes therefore would depress them
  • Deviation would be hypertropic
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27
Q

What would be the deviation. if px has a right superior rectus weakness on dextroelevation?

A

right eye fail to elevate

-becomes hypertropic on dextroelevation

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28
Q

What actions do the inferior rectus muscle have in primary position ?

A

1st - depression and the 2nd and 3rd we decide from using RADSIN.

  • the inferior rectus muscle is a rectus muscle therefore will adduct the eyes
  • if it is however not superior therefore the final action is extortion/ excocycloduction
29
Q

What would happen to the eye if this inferior rectus muscle was weak in primary possession ?

A

1st- hypertropic- as the eye fails to depress
2nd- fail to pull in nose- hence exotropic- abduct
3rd-intortion

30
Q

What actions do the Inferior rectus have when it is being maximally used ?

A

in the right eye - right inferior rectus - eye is looking out away from nose
-in the left eye- left inferior rectus- when looking out away from nose

31
Q

What actions does inferior rectus have when eye is looking away from the nose (abducted) ?

A
  • Last week lecture
  • when we abduct the eye by 23 degrees, the muscle axis of rotation coincides with the fixed x axis
  • as x controls vertical movement - as inferior rectus depresses the eye , as the IR is weak therefore the eye would fail to depress- hence become hypertropic
32
Q

What actions do the superior oblique muscle have in primary position ?

A

1st is depression and 2nd abduction and 3rd incycloduction ( both 2nd and 3rd are decided by RADSIN ).

  • the superior oblique is not a rectus muscle and therefore it is not going to adduct the eyes , it will hence abduct the eyes.
  • it is a superior therefore the final action is incyloduction/intortion
33
Q

What is the deviation if the superior oblique muscle IS WEAK in the primary position of gaze ?

A

1st- hypertropic
2nd- esotropic
3rd- extorted

34
Q

What actions do the superior oblique have when they are being maximally used ?

A

LSO - being maximally used when eyes are looking into dextrodepression- when eye is adducted - looking in towards the nose
RSO- being maximally used when eyes are looking into laevodepression- right eye is adducted - looking in towards nose

35
Q

What action does the Superior oblique have in adduction ?

A

if the eyes adducted into the nose by 54degrees, the muscle axis of rotation will coincide with the x axis - Turning the superior oblique into a pure depressor

36
Q

What happens if the superior oblique muscle is weak ?

A

the eye would fail to depress therefore would be hypertropic

37
Q

What actions does the inferior oblique muscle have in primary position ?

A

1st - elevation
2nd abduction and 3rd extort
-not a rectus therefore it will abduct the eyes
- it is inferior oblique therefore will not incycloduct the eye it will excycloduct/ extort.

38
Q

What would happen if inferior oblique was weak in primary position ?

A

1st- hypotropic
2nd esotropic
3rd-intort

39
Q

What actions does the inferior oblique have when they are being maximally used ?

A

in left eye - when LIO is being maximally used it is looking in towards the nose (ask px to look into dextroelevation)
in right eye- when RIO is being maximally used it is looking towards the nose
(ask px to look into laevoelevation)

40
Q

What actions does the inferior oblique have when looking towards the nose (adduction) ?

A
  • when looking intowards the nose at 51 degrees of adduction
  • the muscle of axis coincides with fixed x axis and turns into a pure elevator
41
Q

What would happen if the inferior oblique was weak ?

A
  • wouldnt be able to elevate the eye

- Hypotropic

42
Q

What is the agonist?

A

the muscle which causes it
e.g if px wanted to look into laevoversion , the muscle that must contract in order to look into the laevoversion is the left lateral rectus
so the agonist is the = left lateral rectus - the muscle which started it all off

43
Q

Can the agonist work by itself ?

44
Q

What must happen in order for the left eye to look into the laevoversion ?

A
  • the agonist cannot work on its own
  • something must relax
  • that is the antagonist
45
Q

What is the antagonist ?

A

muscle that works opposing to the agonist
if px wanted to look to left side- the left lateral rectus has to contract but in order to let that happen the left medial rectus would have to relax.
- the agonist contracts= the antagonist relaxes

46
Q

What is the Sherrington law?

A

-whenever an agonist contracts an equal inhibitory input is sent to to the antagonist to relax

47
Q

What is the antagonist if the agonist is the MR?

A

the lateral rectus

48
Q

What is the antagonist if the agonist is the LR?

A

the medial rectus

49
Q

What is the antagonist if the agonist is the IO?

A

the superior oblique

50
Q

What is the antagonist if the agonist is the SO?

A

the inferior oblique

51
Q

What is the antagonist if the agonist is the SR?

A

the inferior rectus

52
Q

What is the antagonist if the agonist is the IR?

A

the superior rectus

53
Q

When we directly elevate of depress the eye what does it require ?

54
Q

What are the 2 muscles when directly elevating the eye in the right eye ?

A

the RSR and RIO (Are the agonist as they need to contract )

55
Q

What are the 2 muscles when directly elevating the eye in the LEFT eye ?

A

the LIO and LSR (WHICH are the agonist ) as need to contract

56
Q

What is the antagonist when the RSR and RIO are the agonist ?

A

RIR and RSO

57
Q

What is the antagonist when the LIO and LSR are the agonist ?

A

LSO and LIR

58
Q

What happens when you tilt your head to the right shoulder in your RIGHT EYE ?

A 
the right eye intorts and slightly elevates 
-use RADSIN
-the right superior rectus and oblique that are bringing introtion
as SIN (superior intort)
59
Q

What is the antagonist in the right eye as it is intorted ?

A

RIGHT inferior rectus and right inferior oblique

60
Q

What happens when you tilt your head to the right shoulder in your LEFT EYE ?

A
  • the left eye extorts
  • SIN- inferior extorts the eye
  • the left inferior rectus and left inferior oblique
61
Q

What is the antagonist in the left eye as it is extorted ?

A

Left superior rectus and left superior oblique

62
Q

What happens when you tilt your head to the left shoulder in your LEFT EYE ?

A

left eye is intort

-SIN - left superior rectus and oblique that is firing

63
Q

What is the antagonist in the left eye as it is intorted ?

A

left inferior rectus

left inferior oblique

64
Q

What happens when you tilt your head to the left shoulder in your RIGHT EYE ?

A
  • right eye extorts

- SIN - RIGHT inferior rectus and right inferior oblique that is firing

65
Q

What is the antagonist in the right eye as it is extorted ?

A

Right supe§rior rectus and right superior oblique

66
Q

What action does the RSR mainly have when you carry out ocular motility on dextroelevation ?

67
Q

What action does the RSO mainly have when you carry out ocular motility on laevo depression?

A

depression

68
Q

What muscles will contract in the Right eye when you tilt your head to the Left?

A

Right inferior rectus, right inferior oblique

OV2018 binocular vision (15 decks)

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