The sphenoid bone is outlined in each view. E, Conchal type sphenoid bone. F, Bone with presellar type sphenoid sinus. G, Bone with sellar type sphenoid sinus and well-defined sphenoid ostia. H, Bone with sellar type sphenoid sinus with poorly defined sphenoid ostia and obliquely oriented sphenoidal septae. (Images courtesy of AL Rhoton, Jr.)