The sphenoid sinus is one of the four paired paranasal sinuses that is contained within the body of the sphenoid bone. The sphenoid sinuses vary in size and shape, and owing to the lateral displacement of the intervening septum they are rarely symmetrical. They cannot be palpated during an extraoral examination. The sphenoid sinus is one of the four paired paranasal sinuses that is contained within the body of the sphenoid bone. The sphenoid sinuses vary in size and shape, and owing to the lateral displacement of the intervening septum they are rarely symmetrical. They cannot be palpated during an extraoral examination.