142 



J. PARSONS SCHAEFFER 



narrow and curved ductus nasofrontalis. The duct communi- 

 cates with the recessus frontahs. There are very definitely two 

 ostia frontalia to the duct, one proximal and the other distal in 

 position. The duct is encroached upon by a cellula ethmoidalis 

 anterior (really a second sinus frontalis) which developed from 

 the second frontal furrow. The slightest swelling of the mucosa 

 of such narrow and tortuous ductus nasofrontales (figs. 7 and 10) 

 would, of course, occlude its lumen. In some instances the 



ductus /fasofrot/tah. 

 In/u7>dib.eth. , ^ 

 Concha Ttas. med. 



OstJ.um.maxillare - //- -^x^ - 



X..--- 





. CeJlultz eth.a/ft. 

 _, CeJ/vIa etk. a f itemed). 



^,'^ [_r^"' 0stJiJ7/f. spJienoidale 

 ..BvUaeth 



auditivae 





, \^sfmmphan/n- 



Fig. 12 Dissection from an adult. Recessus frontalis exposed. Note the 

 discontinuous channels, i.e., the ductus nasofrontalis and the infundibulum 

 ethmoidals. 



ductus nasofrontalis is roomy, possessing large proximal and 

 distal ostia, thus affording a better drainage channel for the sinus 

 frontalis (fig. 13). 



The ductus nasofrontalis with its proximal ostium or in the 

 absence of a true duct, the proximal ostium frontale (in the 

 latter the distal ostium frontale is wanting) , bears a varied rela- 

 tion to the ventral extremity of the infundibulum ethmoidale. 

 The latter usually ends blindly lateral to the terminal portion of the 

 ductus nasofrontalis. The infundibulum ethmoidale and the due- 



