146 THE NASAL ACCESSORY SINUSES IN MAN 



meatus medius via the infundibulum and the hiatus semi- 

 lunaris. Thus in these cases there is a close relationship 

 between the sinus frontales and the sinus maxillares, since 

 the ostium maxillare in all cases is situated in the infero- 

 lateral wall of the infundibulum. 



SUPERNUMERARY SINUS FRONTALES 



Ordinarily only one frontal sinus develops on each side, 

 but in a few instances supernumerary sinuses are found. 

 The term supernumerary sinuses must not be used in describ- 

 ing sinuses incompletely divided by a partial septum or 

 septa, but is restricted to cases in which more than one 

 distinct process of pneumatization from either lateral nasal 

 wall develops sufficiently to invade the vertical portion of the 

 frontal bone the sinuses being separated by a complete 

 septum and having independent ostia. 



It would be possible to have supernumerary sinuses de- 

 velop by extensions from two cellulse infundibulares, from 

 two cellulae frontales, or from any combination of the above- 

 described five routes of development of sinus frontales. 



In 101 cases (202 frontal areas) having mucosa attached, 

 we found two cases showing the presence of two frontal 

 sinuses on each side, and three cases which had two sinuses 

 on one side and the usual one sinus on the other side. Thus 

 of the 202 frontal areas, 7 of them had double sinuses. In 

 4 of these instances the double sinuses were on the right side, 

 and in 3 on the left. The ways in which these 7 double 

 sinuses originated were as follows: 



1. By the extension of two cells medial to the processus 

 uncinatus (cellulse frontales) in three instances (Fig. 36). 



