superior oblique muscle (SO)

Introduction

Extraocular muscle in the orbit.

Origin

above the medial margin of the optic canal

Insertion

• by a tendon passing through the trochlea (pulley), then reflected backward & downward, & laterally to the sclera between the superior & lateral recti

Action

• primary: intorsion
• secondary: depression & abduction

Innervation

trochlear nerve (CN IV)

Physical examination

Test: ask patient to look downward & inward

More general terms

• extraocular muscle (EOM)

Additional terms

• trochlea