Anatomy

Origin

The inferior oblique originates from the maxillary bone, from the medial part of the floor of the orbit in a small depression just underneath the lacrimal fossa (fossa of the lacrimal sac). Unlike the other extraocular muscles, it does not generate from the common tendinous ring (anulus of Zinn)

Insertion

It inserts into the posterior, inferior, and lateral surface of the eyeball

Nerve

Oculomotor nerve (III cranial nerve)

Actions

The actions of the inferior oblique include extortion (external rotation), elevation and abduction of the eye. The inferior oblique therefore turns the eye up and outwards with lateral rotation