What Is a Sphenoid Sinus?
The sphenoid sinus is an air-filled cavity which surrounds the sphenoid bone in the skull. Everyone has two sphenoid sinuses, with each sinus being around the size of a grape. These sinuses are asymmetrical in shape, and they drain into the back of the nose. Over the course of childhood and adolescence, the sphenoid sinuses grow and settle into their final shapes, with everyone having slightly different patterns in their sinuses; sometimes, sinus anatomy can even be used like a fingerprint to identify someone.
