The sphenoidal sinus (or sphenoid sinus, latin: sinus sphenoidalis) lies within the body of the sphenoid bone relatively posteriorly to the upper part of the nasal cavity. The paired sphenoidal sinuses vary in size and shape, and due to the lateral displacement of the intervening septum they are rarely symmetrical.
Each sphenoidal sinus opens into the sphenoethmoidal recess of the nasal cavity via an aperture (opening) that lies on the anterior wall of the body of the sphenoid.
The arterial blood supply to the sphenoidal sinus is provided by the following vessels:
- posterior ethmoidal branches of the ophthalmic arteries,
- nasal branches of the sphenopalatine arteries.
The venous blood is drained via the posterior ethmoidal veins.
The mucosa of the sphenoidal sinus is receives sensory innervation from the following nerves:
- posterior ethmoidal branches of the ophthalmic nerve,
- orbital branches of the pterygopalatine ganglion.