General Medical Information

Maxillary Sinus

Susan D. John
Michael D. Maves

The maxillary sinus usually is the largest of the paranasal sinuses and is situated in the body of the maxilla. Its anterior wall is the facial surface of this bone, and its posterior wall is the infratemporal surface. Its medial wall is that of the nasal cavity. The roof of the maxillary sinus is also the floor of the orbit, and it also may be affected in blowout fractures of the orbit. The maxillary sinus drains into the middle meatus of the nasal cavity. The roots of the posterior molar teeth may extend into the sinus. The maxillary sinus is bounded posteriorly by the pterygomaxillary fossa, through which course the terminal branches of the internal maxillary artery. These vessels can be approached through the maxillary sinus for relief of epistaxis.