Download 1. List primary and secondary actions of the six extra ocular muscles

1. List primary and secondary actions of the six extra ocular muscles.
Muscle
primary action
secondary
action
tertiary
action
testing position
LR
abduction
none
none
abduction
MR
adduction
none
none
adduction
SR
elevation
intorsion
adduction
up and out
IR
depression
extorsion
adduction
down and out
IO
extorsion
elevation
abduction
up and in
SO
intorsion
depression
abduction
down
2. Explain the difference between the cover/uncover test and the alternate
cover test.
Cover/uncover test is the basic examination for the patient with a manifest squint
(tropias). This is a monocular test designed to reveal a squint or strabismus. When
the non-squinting eye is uncovered, the strabismic eye which has temporarily taken up
fixation will return to its original position ie; nasally in a convergent squint, temporally in
a divergent squint.
Alternate cover test is the basic examination for the patient with an underlying latent
squint (phorias). In this test, both eyes are straight at the beginning and end of the
procedure, one eye is covered for about 2 seconds and then quickly moved to cover
the other eye. As the occluder is moved from the first eye a small compensatory
movement may be identified ie. nasally in exophoria or laterally in esophoria.