The maxillary sinuses, one on each side, are the largest of the paranasal sinuses and completely fill the bodies of the maxillae (Fig. 8.235A,B). Each is pyramidal in shape with the apex directed laterally and the base deep to the lateral wall of the adjacent nasal cavity. The medial wall or base of the maxillary sinus is formed by the maxilla, and by parts of the inferior concha and palatine bone that overlie the maxillary hiatus.