In a report1 of an earlier study of a small group of maxillary sinuses it was pointed out that what is called the maxillary ostium or orifice is usually a canal.
The present report deals with a study of 102 antrums from cadavers, including the first group, just mentioned, and is concerned with two problems: (1) Is the so-called natural ostium of the maxillary sinus an orifice (window, ostium) or a canal? (2) What are the various types of ostiums or canals found in the maxillary sinus?
The procedure for deciding whether the opening from the infundibulum ethmoidale into the maxillary sinus was an ostium or a canal was as follows: The middle turbinate was displaced or cut away so as to expose the middle meatus. Next, the anterior or facial wall of the antrum was removed, so as to expose the interior of the antrum. Then, with