sphenoidale

The sphenoid bone, or os sphenoidale in Latin, is a single, midline bone at the base of the skull. It forms a central part of the cranial floor and contributes to the walls of the orbits and the posterior nasal cavity. It articulates with nearly all surrounding bones, making it a keystone of the skull.

Anatomy and structure: The bone consists of a central body, two wings (greater and lesser), and two pterygoid processes. The body contains the sphenoidal sinuses and houses the sella turcica, a saddle-shaped depression that accommodates the pituitary gland, with the tuberculum sellae anteriorly and the dorsum sellae posteriorly. The greater wings form portions of the middle cranial fossa and the posterior orbit, while the lesser wings contribute to the roof of the orbit and the optic canal. The pterygoid processes project downward to provide attachment points for the pterygoid muscles.

Openings and connections: The sphenoid bone features several important openings and fissures, including the optic canal (optic nerve and ophthalmic artery) in the lesser wing; the superior orbital fissure; the foramen rotundum (transmitting V2, the maxillary nerve); the foramen ovale (transmitting V3, the mandibular nerve); and the foramen spinosum. The foramen lacerum lies at the skull base where it borders the sphenoid, temporal, and occipital bones. The sphenoid sinus is located within the body.

Clinical relevance: Because the sphenoid forms a central portion of the skull base and part of the orbital walls, fractures or surgical procedures in this region can affect vision and multiple cranial nerves. Sphenoidal sinusitis can impact nearby structures, and lesions of the sella turcica may affect the pituitary gland.