The Developing Human Sphenoid Bone: Linking Embryological Development to Adult Morphology

The human sphenoid bone (SB), centrally located at the cranial base, is structurally and developmentally complex. It arises from multiple cartilaginous precursors and undergoes both endochondral and intramembranous ossification, forming essential elements such as the sella, orbital walls, and numerous foramina. This review integrates embryological, anatomical, and radiological findings to present a comprehensive view of SB development and variation. Embryological studies reveal a layered ossification sequence, with accessory centers in the presphenoid and basisphenoid that influence adult morphology and variants, such as the caroticoclinoid foramen. In adulthood, the SB consists of a central body, paired greater and lesser wings, and the pterygoid processes, which articulate with key craniofacial bones and transmit vital neurovascular structures. Notable variants include duplication or absence of foramina, ossification of ligaments such as the pterygoid and pterygospinous ligaments, and the formation of bony bridges among the clinoid processes. These variants may affect cranial nerve trajectories and surgical access, posing potential risks during neurosurgical, endoscopic, and dental interventions. Emissary structures such as the sphenoidal emissary foramen and the newly described sphenopterygoid canal underscore the region's vascular complexity. Additionally, variations in the optic and Vidian canals, as well as the superior orbital fissure, can also impact surgical approaches to the orbit, sinuses, and skull base. Understanding the full spectrum of sphenoid bone embryogenesis and morphology is essential for safe clinical practice and practical radiological imaging.