NASOFRONTAL REGION IN MAN 



139 



an additional frontal pit which gave rise to the sinus frontalis 

 was present in the position of the ductus nasofrontalis is, of course, 

 impossible to say. Two of the cellulae ethmoidals anterior are 

 separated by a considerable interval. This space may have been 

 the second frontal pit. Again, the two frontal pits in question 

 (cellulae ethmoidales anterior) may have been crowded apart by a 



Sh/ffs fro?/ talis 



Trobem ducd^s.y/asof/o/ita//. 



Sinus {ro^ftcflis — 



Infiu/c/iij. (t/i . 



T/'OC. UJfciu atrj s 

 BvJia et/,..---il[i 



^. Cellulae etli.ant. 



,}fi/pophi/si.s cereiri 



Sinvs sphowidalis 



X- 





Co/uka. Jias. vmd 



t/UM plf.ari/ucfeum 

 f/jbae aiiditivae 



\ 



Fig. 10 Dissection from an adult. Note the sinus frontalis present in dupli- 

 cate, the proximal ostia frontales in relation to the recessus frontalis, and the 

 ventral termination of the infundibulum ethmoidale. See text. 



bullous-like ventral and cephalic growth of the infundibulum eth- 

 moidale in the establishment of the sinus frontalis. My experi- 

 ence has been that it is unusual for the sinus frontalis to arise 

 from the infundibulum ethmoidale. 



Drainage from the sinus frontalis in such instances (fig. 8) 

 would almost wholly pass into the infundibulum ethmoidale, and 

 via the latter to the ostium maxillare, thence into the sinus maxil- 

 laris. Should the floor of the infundibulum ethmoidale in such 

 cases be largely replaced by an elongated ostium maxillare (a 



