extra ocular eye movement Flashcards
importance of eye movement
- the eyes move to initiate and maintain fixation by directing the line of sight , important to keep the image on the retina
- also important to follow objects thought saccades and pursuits
listing plane
cuts eye transverse into posterior and anterior segments
axes of fick
the glob rotates on the this
X axis
eye rotates up and down
Y axis
eye makes torsional rotations like a wheel
tilt head side to side
Z axis
eye rotates from side to side
“zide to zide”
Duction
movement or rotation of one eye around the axes of fick (monocular)
evaluated with the other eye closed and having the pt move the eye in all directions of gaze
version
binocular, simultaneous and conjugate eye movements or rotation of both eyes
torsion
twist of the eye clockwise or counterclockwise around the axes of fick
intorsion
top of the eye rotates towards nose
extorsion
top of the eye rotates away from nose
conjugate eye movements
binocular movement where the visual axis of both eyes are in the same direction to maintain fixation with both eyes. Both eyes move in the same direction, by the same amount
conjugate torsion
twists the eyes in the same direction, clockwise or counterclockwise when the head is tilted to the right or the left
vergence
disoncjugate eye movement where the eyes rotate in opposite directions
-looking at a pen close to nose, eyes are not looking in the same direction
convergence
both eyes rotate in to maintain fixation, for instance, when reading
divergence
divergence
both eyes rotate out, hard to see
How many extraocular muscles are there?
6
4 recti, 2 oblique
recti muscles
superior rectus
inferior rectus
medial rectus
lateral recuts
oblique muscles
superior oblique
inferior oblique
horizontal recti muscles
in primary gaze, they are horizontal movers around the vertical Z axis
Medial rectus
- moves the eye to the nose (ADDuction)
- innervated by CN3
- inserts 5.5mm from nasal limbus
lateral rectus
- moves eye away from the nose (ABduction)
- CN6
- inserts 6.9mm from temporal limbus
vertical recti muscles
similar to horizontal recti muscles, they also insert in front of the equator
superior rectus
- primary action is to move the eye up (elevation)
- secondary action: intorsion
- tertiary action: ADDuction
- CN3
- inserts 7.7mm from superior limbus