EOM ANATOMY AND KINEMATICS Flashcards
Corresponds to the equatorial plane of the globe
Listings plane
Point where there is zero velocity during any eye movement
Center of rotation
The center of rotation is not a fixed point
It is a locus of points
The center of rotation is space centroid/ body centrode
Due to the fact that due rotation is accompanies by small translational movement
Center of rotation is said to be about 13.5mm from
Corneal apex
Rotation of one eye around z axis
Abduction
Rotation of one eye one x axis
Elevation & depression
Rotation of one eye on y axis
Intorsion and extortion
Muscles that originate at the back of the orbit in the common tendinous ring or annulus of zinn
All rectus & superior oblique
Thickest of the EOMS
Medial rectus
Shortest of the eye muscles
Lateral rectus
Longest of the recto muscles
Superior rectus
Longest and thinnest of the EOMS
SO
Originates from the front of the orbit floor on the nasal side
Inferior oblique
Recti muscle attach to the globe ___ mm from the limbus
MR=5
IR=6
LR=7
SR=8
Spiral of tillaux
Attachments of recti muscle form a spiral pattern around the limbus
Actions of the SR
Elevation
Intortion
Adduction
When the SR is looking out temporally
The only action is elevation
When SR is looking in (nasally) the only action is
Intortion
Actions of IR at primary gaze
Depression
Extortion
Adduction
If eye is looking temporally IR purely
Depresses
If eye is turned nasally, IR only
Extorts
As the eye is adducted, SR and IR produce
More torsion but less vertical movement
SR and IR are most effective vertical movers when the eye is
Abducted
When the eye is turned in the SO action is
Pure depressor
When there eye is turned out, SO’s action is pure
Intortion
In primary position SO actions include
Intortion
Depression
Abduction
