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[The anatomy of the maxillary ostium and the middle meatus antrostomy].

Serial cadaver dissections were performed and the anatomy of the natural ostium of the maxillary sinus and its adjacent structures observed. The results showed obvious anatomic variations. In most cases, the maxillary ostium was located in the infundibulum, directly under the orbit. The average distance was 1.1 cm from the maxillary ostium to the anterior maxillary wall, showing the anatomic relationship of the maxillary ostium with the nasolacrimal duct. The close anatomic relationship between the antronasal channel and orbit was demonstrated by radiography. A retrospective review of 70 middle meatal antrostomies was conducted and discussed. The anatomy of the antronasal channel should be well understood by an endoscope sinus surgeon in order to perform the middle meatal antrostomy without injuring the orbit and nasolacrimal duct.