Medial rectus

The medial rectus (Latin: musculus rectus medialis), also called the medial rectus extraocular muscle, is one of the six extraocular muscles that are in control of eye movements. The medial rectus is responsible for turning the visual gaze medially.

Origin

The medial rectus originates from the medial part of the common tendinous ring, and also from the dural sheath of the optic nerve (CN II). The muscle passes horizontally forwards along the medial wall of the orbit, below the superior oblique muscle.

Insertion

The medial rectus inserts into the medial surface of the sclera, approximately 0.2 inches (5.5 mm) from the limbus and slightly anterior to the other recti muscles.

Action

Contractions of the medial rectus turn the eyeball medially. The right and left medial recti acting together are responsible for convergence of the eyes - moving the eyes closer together and turning inward to look at a close object.

Innervation

The medial rectus is innervated by the oculomotor nerve (CN III).

Blood supply

The medial rectus receives arterial blood supply mainly from the ophthalmic artery.