Lesser Wing Of The Sphenoid Bone, Anatomy

Description

Lesser wing of the sphenoid (ala minor) forms a thin, laterally projecting plate at the junction of the anterior and middle cranial fossae. Medially, its root contributes to the optic canal, where the optic nerve (CN II) and ophthalmic artery pass from the cranial cavity to the orbit, while its posterior margin helps outline the superior orbital fissure just inferior to the wing. Anteriorly and superiorly, the lesser wing approaches the frontal bone and the anterior cranial base, and its medial end rises as the anterior clinoid process adjacent to the sella turcica and the cavernous sinus. Sharp edges matter here. Skull base anatomy hinges on this landmark because a few millimeters separate the optic canal, the clinoidal segment of the internal carotid artery, and the orbital apex, so lesions or bone changes around the ala minor can translate into visual loss, painful ophthalmoplegia, or surgical constraint. In aneurysm surgery and tumor resections involving the parasellar region, anterior clinoidectomy requires a precise understanding of the lesser wing’s thickness and its relationship to the optic strut and optic canal roof. The fixed perspective and isolated bony emphasis support clean identification of these borders without distraction from soft tissue. Neuroanatomy and head and neck anatomy courses use this illustration to teach the boundary between anterior and middle cranial fossae, the bony frame of the optic canal, and the superior orbital fissure margin. It also fits well in neurosurgical and ENT skull base manuals, radiology teaching files on orbital apex and parasellar lesions (CT bone window correlation), and patient education diagrams for optic canal decompression planning. Anatomical accuracy verified by SciePro's Medical Advisory Board.