PHYSIOLOGY - Eye movements Flashcards
What is the difference between uniocular and binocular movements?
uniocular movements - duction.
binocular movements - vergence and versions.
What are the six movements of duction? Which axis?
- ADduction (vertical axis - z axis)
- ABduction (vertical axis - z axis)
- SUpraduction (horizontal axis - x axis)
- Infraduction (horizontal axis - x axis)
- Incycloduction (anteroposterior axis/y axis)
- Excycloduction (anteriorposterior axis/y axis)
What is listing’s plane?
x axis and z axis transverse the globe through the equator and form the Listin’gs plane.
What is the difference between versions and vergence eye movements?
versions are CONJUGATE synchronous movements in same direction
vergence are DISJUGATE movement of eyes in opposite directions
For the horizontal recti muscles, why do they only have one primary action?
Their insertion into the eyeball is straight and vertical and in primary position of gaze, their muscle plane co-incides with the visual axis.
Their movement occurs along the z-axis.
Which muscles are activated in dextroversion?
Which muscles are activated in levoversion?
dextro: right LR, left MR
levo: left LR, right MR
at what angle of the globe do the visual and orbital axis co-incide for the vertical recti muscles? Why?
Which muscle action occurs in this plane?
When globe is ABducted at 23 degrees, the visual and orbital axis co-incide allowing primary action of elevation or depression.
When the globe is aDducted at 67 degrees, what happens to the visual and orbital axis? What movements can occur here for vertical recti muscles?
the visual and orbital axis are at 90 degrees to each other of vertical recti muscles. This causes rotational movements.
SR - INTORSION
IR - EXTORSION
In which gaze is the optimal position of globe for testing the function of vertical recti muscles?
ABduction - visual and orbital axis co-incide here.
What are the actions of the vertical recti muscles?
SR: elevation, intortion, adduction
IR: depression, extortion, adduction.
What is the globe angle to allow the visual and orbital axis to co-incide for the OBLIQUES? What action of movement occurs here?
51 degrees ADduction.
IO: elevation
SO: depression.
What is the globe angle to allow visual and orbital axes to be 90 degrees from each other? What action of movement occurs here?
39 degrees ABduction.
IO: extorsion
SO: intorsion.
What is the optimal position for globe testing for the function of the obliques muscles?
ADduction. (visual and orbital axis co-incide)
What are the actions of the obliques?
SO: intorsion, depression, abduction
IO: extorsion, elevation, abduction
What are the muscles acting in supraversion?
What are the muscles acting in infraversion?
- bilateral SR and bilateral IO.
- bilateral IR and bilateral SO