inferior oblique (IO)

Introduction

Extraocular muscle in the orbit.

Origin

• orbital plate of the maxilla lateral to the lacrimal groove

Insertion

• sclera between the superior & lateral recti

Action

• primary: extorsion of the globe (of the eye)
• secondary: elevation & abduction of the globe

Innervation

• oculomotor nerve (CN III) inferior branch

Physical examination

Test: ask patient to look upward & inward

More general terms

• skeletal muscle (voluntary muscle)