The Sinus Mawxillaris in Man. 351 
cavity to open into the infundibulum ethmoidale, thence via the 
hiatus semilunaris into the meatus nasi medius. It must be 
clearly kept in mind that the ostium is located in the superior 
part of the sinus, and that it opens into infundibulum ethmoi- 
dale and not into the hiatus semilunaris as many writers say. 
The ostium maxillare may be either in the most dependent part 
of the infundibulum or in the lateral wall of this channel. This 
opening varies in distance from the hiatus semilunaris from 
1 to 12 mm. This distance is dependent upon the width of the 
processus uncinatus and the resultant depth of the infundibulum 
ethmoidale at this point. 
Fic. 26 (X .66). Drawing of a specimen showing a direct communication 
between the sinus frontalis and maxillaris (indicated by the arrow). 
Note the very large slit-like ostium maxillare. The lateral wall of the infun- 
dibulum ethmoidale is entirely wanting. 
S. Fron., = sinus frontalis; S. Max., = sinus maxillaris; O. M., = ostium max- 
illare. 
The ostium may be round, but as a rule is either oval or ellip- 
tical. In my series of 90 cases it has a great range of dimensions; 
varying from 1 to 20 mm. in length, and from 1 to 6 mm. in width. 
In some cases where the ostium has reached considerable size 
it may almost entirely replace the lateral wall of the infundibu- 
lum ethmoidale, thus forming a long slit-like communication 
