Corpus: Inferior rectus muscle

The inferior rectus muscle is a skeletal muscle that is part of the extraocular muscles responsible for eye movement.

The inferior rectus muscle originates from the common tendinous ring (annulus tendineus communis). It runs in a straight path and attaches to the lower surface of the eyeball (bulbus oculi) on the sclera, just in front of the equator of the eye.

The inferior rectus muscle is innervated by the inferior branch of the oculomotor nerve (cranial nerve III).

The muscle receives its arterial blood supply from the muscular branches of the ophthalmic artery and the orbital branches of the infraorbital artery.

The primary function of the inferior rectus muscle is to depress the eye, moving the eyeball downward (caudally) during contraction. It works in conjunction with the superior oblique muscle to achieve this movement. Additionally, the inferior rectus muscle assists in adducting the eye (moving it inward) and rotating the upper half of the eyeball outward (extorsion).