NASOFRONTAL REGION IN MAN 131 



it is unusiial for the infundibuluin cthmoidale to be directly con- 

 tinuous with a frontal furrow or pit (fig 3). The latter embrj^o- 

 logical fact is significant when one recalls the careless state- 

 ment frequently made without qualification, that in the adult the 

 ''infundibulum ethmoidale is continued upwards as the naso- 

 frontal duct into the sinus frontalis." 



Because of the intimate relations, in the adult, of the infun- 

 dibulum ethmoidale and the ductus nasofrontalis or the sinus 

 frontalis directly, the infundibulum ethmoidale serves, in many 

 instances, as a channel to convey secretion from the sinus fron- 

 talis to the sinus maxillaris. This is enhanced in those cases in 

 which the infundibulum ethmoidale is deep and ends dorsalh^ 

 in a blind pouch, thus directing drainage through the ostium 

 maxillare into the sinus maxillaris (figs. 8 and 12). In other 

 words the sinus maxillaris is often a cesspool for infectious ma- 

 terial from the sinus frontalis and certain of the anterior group 

 of cellulae ethmoidales 



The above well known clinical fact has doubtless led to the 

 erroneous belief that the infundibulum ethmoidale is, in the 

 majority of instances, directl}' continuous anatomically with the 

 nasofrontal duct or, in the absence of the latter directly with 

 the sinus frontalis. The inference is also wrongly drawn that 

 in many cases the sinus frontalis is embryologically a direct 

 outgrowth of the ventral and cephalic end of the infundibulum 

 ethmoidale. From what has been said previously on the em- 

 bryology, it is needless to enter further into a discussion here. 

 Suffice it to say that it is not a common adult anatomic condi- 

 tion to find the infundibulum ethmoidale directly continuous 

 with the ductus nasofrontalis, or in the absence of the latter 

 with the ostium frontale. There are in many instances close 

 relationships established, even a contiguity, but a direct contin- 

 uity is an occasional occurrence only. According to the series 

 worked it is, likewise, not common for the sinus frontalis to have 

 its genesis in the infundibulum ethmoidale. 



It should, however, be pointed out that in probably as many 

 as 50 per cent of adult cases the relationship is so intimate be- 

 tween the infundibulum ethmoidale and the sinus frontalis or 



