Greater wing of sphenoid

The greater wing or ali-sphenoid of the sphenoid bone is a process which projects from either side of the lower part of the sphenoid body, at a common junction with the pterygoid process . It is a paired structure, which curves upward, backward and laterally from each side of the sphenoid body, which can be likened to the extended wings of a bat . Both wings also have a triangular process projecting inferiorly which is known as the spine of the sphenoid bone.

Gross Anatomy

The greater wing of the sphenoid features superior, lateral and orbital surfaces.

The superior surface features:

• foramen rotundum: transmits the maxillary branch of the trigeminal nerve
• foramen ovale: transmits the mandibular division of the trigeminal nerve, accessory meningeal artery and (occasionally) the lesser petrosal nerve
• foramen spinosum: transmits the middle meningeal artery and meningeal branch of the mandibular nerve
• foramen Vesalii: variable presence, transmits small vein of cavernous sinus

The lateral surface features:

• infratemporal crest: a transverse ridge dividing the lateral surface in two parts
  • temporal: forms part of the temporal fossa and provides attachment for the temporalis
  • infratemporal: forms part of the infratemporal fossa and provides attachment for the lateral pterygoid
• spina angularis: serves as attachment for sphenomandibular ligament and the tensor veli palatini. Grooved by the chorda tympani, medially, and the auriculotemporal nerve, laterally

The orbital surface features:

• inferior margin: forms postero-lateral boundary of the inferior orbital fissure
• medial margin: forms lower boundary of the superior orbital fissure
  • a tubercle at its centers serves as an attachment to the inferior head of the lateral rectus muscle
  • upper part of the margin is notched by the transmission of a recurrent branch of the lacrimal artery
• lateral margin: articulates with the zygomatic bone, inferiorly, and frontal bone, superiorly

Articulations

The lateral margin of the posterior border of greater wing articulates with the anterior border of petrous temporal bone.

The posterior most part of the greater wing projects as a triangular process, sitting within the angle of the junction between the squamous and petrous portions of the temporal bone.

The tip of the great wing articulates with the parietal bone at the pterion.

Variant anatomy

• sphenoidal emissary foramen (occasionally present) it is a small aperture medial to the foramen ovale, opposite the root of the pterygoid process; it opens below near the scaphoid fossa and transmits a small vein from the cavernous sinus
• foramen petrosum (occasionally present), a small opening between the foramen spinosum and foramen ovale, for transmission of the lesser petrosal nerve
• common variant of foramen spinosum where the meningeal artery passes through foramen ovale instead of foramen spinosum

Osseous development

The greater wings of the sphenoid are the only bony structures of the skull which undergo both intramembranous and endochondral ossification.

Related pathology

Traumatic injury

• injuries most commonly associated with fractures of the sphenoid are orbital fractures and mid-face fractures which usually occur following high energy trauma
• fractures of the greater wing of the sphenoid are relatively uncommon and mostly associated with lateral orbital wall fractures along the broad spheno-zygomatic suture

Surgical relevance

• lateral orbital decompression surgery for exophthalmos
• lateral orbital wall fracture repair
• emergent surgical relief of optic nerve compression