Sphenoidala

Sphenoidala is not a widely used term in contemporary anatomy; when encountered, it often refers to the sphenoid bone (os sphenoidale) or to structures associated with it in older or Latin-language sources. The standard English form is sphenoid bone, a central element of the cranial base.

The sphenoid bone is a single, complex bone located at the skull base, wedged between the frontal, temporal, ethmoid, and occipital bones. It contributes to the anterior and middle cranial fossae, forms part of the orbital walls, and houses the sella turcica, which contains the pituitary gland. The bone comprises a central body, two pairs of wings (greater and lesser), and two pterygoid processes that extend downward.

Within the body lie the sphenoid sinuses, and the sella turcica contains a bony floor known as the hypophyseal fossa, with the tuberculum sellae and dorsum sellae forming its rims. The greater wings contribute to the middle cranial fossa and the orbits, while the lesser wings help delineate the anterior cranial fossa and contain openings for the optic canals. The pterygoid plates provide attachment points for muscles of mastication and other soft tissues.

Developmentally, the sphenoid bone forms from multiple ossification centers in early life, with components arising from endochondral and intramembranous ossification and fusing as the skull matures.

Clinically, the sphenoid region is notable for its proximity to critical structures: the pituitary gland in the sella, the optic nerves near the optic canals, and the internal carotid arteries adjacent to the body. Sphenoid sinusitis can cause head and facial pain, and tumors or fractures in this region can impact vision or endocrine function.

Etymology: the term derives from Greek and Latin roots meaning wedge-shaped, reflecting the bone’s wedged position at the skull base.