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Lesser Wing of the Sphenoid

ala minor ossis sphenoidalis

The lesser wings of the sphenoid are two triangular plates projecting laterally from the upper part of the sphenoid body, forming the posterior part of the orbital roof and the anterior boundary of the middle cranial fossa. Their posterior free border, the sphenoid ridge, forms the anterior clinoid processes medially and separates the anterior and middle cranial fossae. The optic canal lies between the lesser wing and the body of the sphenoid, transmitting the optic nerve (CN II) and the ophthalmic artery.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The optic canal through the lesser wing is the critical structure threatened by sphenoid wing meningiomas, pituitary apoplexy, and orbital apex tumours, producing visual loss and optic atrophy from optic nerve compression. The anterior clinoid process is drilled to expose the intracavernous carotid artery during skull base surgery. The lesser wing forms the orbital roof and is decompressed in endoscopic orbital apex surgery. Fractures through the lesser wing can damage the optic nerve.

Pathology

Common Injuries & Conditions

Traumatic Optic Neuropathy

High-energy craniofacial trauma can fracture the lesser sphenoid wing through the optic canal, causing immediate or delayed optic nerve injury with painless visual loss, managed with high-dose corticosteroids or surgical decompression of the optic canal in selected cases.

Anterior Clinoid Meningioma

Meningiomas arising from the anterior clinoid process of the lesser wing compress the optic nerve, the internal carotid artery, and the cavernous sinus, producing a combination of visual loss, ptosis, and ophthalmoplegia that requires complex skull base surgical removal.