Inferior Rectus Muscle Displayed Alone in the Skull

Description

Arising from the common tendinous ring (anulus tendineus communis) at the orbital apex, the inferior rectus muscle courses anteriorly along the orbital floor to insert on the inferior sclera, just posterior to the corneoscleral limbus. Its belly lies inferior to the globe and inferior to the optic nerve, with the inferior oblique sweeping laterally beneath it toward the posterolateral sclera. Medially, the inferior rectus sits adjacent to the medial rectus near the anterior orbit, while the lateral rectus remains separated by the inferior oblique and intervening orbital fat. Primary action is depression of the eye in abduction, with secondary adduction and extorsion, so its line of pull matters when you teach H-pattern testing or interpret diplopia. Entrapment after an orbital floor blowout fracture commonly tethers the inferior rectus or its fascial sleeve, producing restricted upgaze and vertical diplopia, and this relationship to the maxillary sinus floor is why surgeons scrutinize coronal CT sections. Strabismus surgery also relies on this anatomy: recession or resection is planned with respect to the inferior rectus insertion and nearby anterior segment circulation. Use this artwork for medical school head and neck anatomy, ophthalmology and otolaryngology teaching sets, and for surgical atlases covering orbital trauma repair, inferior rectus recession, or transconjunctival approaches to the orbital floor. A strong fit for figures accompanying radiology primers that correlate extraocular muscle position on cross section imaging with clinical motility deficits. Anatomical accuracy verified by SciePro's Medical Advisory Board.