Medial Rectus Muscle

Description

Arising near the annulus of Zinn at the orbital apex, the medial rectus muscle courses anteriorly along the medial orbital wall to insert on the sclera just anterior to the equator of the globe, opposite the lateral rectus. The cornea and anterior sclera define the anterior pole, while the extraocular recti form a sleeve around the posterior half of the eyeball, with the medial rectus lying medial to the optic nerve as it approaches the posterior globe. Small bluish linear elements are consistent with neurovascular structures in the intraconal space, where the oculomotor nerve’s inferior division enters the medial rectus on its deep surface. Relative shortness of the medial rectus is emphasized by its compact belly and tendon compared with the other rectus muscles. Medial rectus anatomy matters most when you are teaching horizontal gaze and when you are planning strabismus surgery. Tightness or overaction produces esotropia, while paresis from an oculomotor nerve lesion limits adduction and can present with diplopia and an abducted eye position. Surgeons look for the tendon’s insertional distance from the limbus and the muscle’s relationship to adjacent recti when performing recession or resection, and the medial wall proximity explains why scarring or medial orbital trauma can restrict adduction. This relationship is easy to misjudge without a clean orbital orientation. Use this artwork in head and neck anatomy courses, ophthalmology teaching files on extraocular muscle actions, and surgical atlases covering medial rectus recession, resection, and transposition procedures. It also suits patient education materials explaining esotropia, oculomotor palsy, and postoperative alignment goals. Anatomical accuracy verified by SciePro's Medical Advisory Board.