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Lesser wing of sphenoid

The lesser wing of the sphenoid is a thin, triangular, horizontally oriented bony projection forming part of the anterior cranial fossa and contributing to the roof of the orbit. It extends laterally from the sphenoid body and contains the optic canal, a crucial passage for the optic nerve and ophthalmic artery.

Its superior surface forms part of the frontal lobe floor, while the inferior surface contributes to the orbital roof, making it a key structural element of the skull base, orbit, and intracranial–extracranial boundaries. Medially, it terminates at the anterior clinoid process, which anchors the tentorium cerebelli.

Because of its proximity to critical neurovascular structures—optic nerve, internal carotid artery, cavernous sinus—it is a major landmark in neurosurgical planning, skull base approaches, and orbital surgeries.

Synonyms

  • Orbital wing of sphenoid (older terminology)

  • Ala minor ossis sphenoidalis

Location and Structure

  • Position: Forms the posterosuperior part of the orbit and the posteromedial portion of the anterior cranial fossa.

  • Shape: Thin, triangular, and shelf-like, projecting horizontally from the sphenoid body.

  • Key features:

    • Optic canal: Pierces the base of the lesser wing; transmits optic nerve and ophthalmic artery.

    • Anterior clinoid process: Medial extension providing dural attachment.

    • Superior surface: Smooth, supporting frontal lobe.

    • Inferior surface: Forms orbital roof and upper margin of the superior orbital fissure.

Relations

  • Superiorly: Frontal lobes of the brain and anterior cranial fossa dura

  • Inferiorly: Orbit, orbital contents, and ocular muscles

  • Medially: Sphenoid body and optic canal

  • Laterally: Frontal bone articulation

  • Posteriorly: Roof of superior orbital fissure and cavernous sinus region

  • Anteriorly: Posterior aspect of frontal bone

Attachments

  • Dural attachments:

    • Anterior clinoid process anchors the tentorium cerebelli

    • Dura of anterior cranial fossa attaches broadly along superior surface

  • Ligamentous/membranous:

    • Optic strut forms part of the optic canal boundary

    • Forms upper margin of the superior orbital fissure, separating it partially from optic canal

Function

  • Forms part of the anterior cranial fossa, supporting frontal lobes

  • Contributes to the orbital roof, protecting orbital contents

  • Houses the optic canal, providing a protected passage for the optic nerve

  • Serves as a structural anchor for the tentorium cerebelli

  • Provides important surgical and anatomical landmarks for skull base and orbital pathways

Clinical Significance

  • Fractures: Blowout trauma, skull base fractures, or orbitocranial injuries may involve the lesser wing

  • Optic canal compression: From fractures, tumors, mucoceles, or inflammation leading to visual deficits

  • Meningiomas: Common along the sphenoid wings, causing hyperostosis

  • Cavernous sinus or ICA pathology: May extend toward the lesser wing region

  • Surgical navigation: Critical in pterional craniotomy, optic nerve decompression, and clinoidectomy

MRI Appearance

T1-weighted images:

  • Cortical bone: Very low signal (black)

  • Bone marrow (limited in lesser wing): Small fatty marrow pockets may appear bright

  • Adjacent structures:

    • Frontal lobe: intermediate gray signal

    • Orbital fat: bright

  • Pathology:

    • Meningioma: iso- to hypointense mass with dural tail

    • Hyperostosis: cortical thickening with low-signal bone expansion

T2-weighted images:

  • Bone cortex: Low signal

  • Marrow: Bright but limited

  • Optic nerve: Intermediate signal within optic canal

  • Pathology:

    • Hyperostosis: low-signal thickened bone

    • Inflammatory or neoplastic lesions: hyperintense soft-tissue masses

    • Mucocele extension: bright T2 signal encroaching on optic canal

FLAIR:

  • Bone: Dark signal

  • Orbital and intracranial soft tissues: Clear distinction

  • Pathology:

    • Adjacent edema in frontal lobe: hyperintense

    • Periosteal reaction or meningioma infiltration: heterogenous intermediate-to-hyperintense

T1 Fat-Sat Post-Contrast:

  • Normal bone: No intrinsic enhancement

  • Enhancing lesions:

    • Meningioma: intense homogeneous enhancement along lesser wing

    • Neoplastic infiltration: strong irregular enhancement

    • Inflammatory changes: patchy dural or periosteal enhancement

    • Optic nerve sheath meningioma: tram-track enhancement around optic nerve

CT Appearance

Non-Contrast CT:

  • Cortex: High-density, sharply marginated bone

  • Marrow: Small areas of lower-density cancellous bone

  • Key advantages:

    • Excellent for fractures of the orbital roof or optic canal

    • Detects hyperostosis in sphenoid wing meningiomas

    • Clear visualization of optic canal narrowing

MRI image

Lesser wing of sphenoid -img-00000-00000

X Ray image

x ray facial bone - Copy (2)

CT VRT 3D image

Lesser wing of sphenoid bone 3d