NASOFRONTAL REGION IN MAN 



129 



in some instances early in extrauterine life. Killian operated 

 upon a diseased sinus frontalis in a child fifteen months old. As 

 statetl before, the recessus frontalis of the meatus nasi medius 

 is demonstrable as early as the fourth fetal month. During late 

 fetal life the recessus frontalis becomes complex by the formation 

 of frontal furrows or pits, etc. One is not justified at this time 

 to hazard an opinion as to the specific point in the recessus 

 frontalis from which the sinus frontalis will ultimately develop. 



Feces s /J s nwifaJis . 



Iroc. 7jf/c>?/afi' s 



Concha nas. sup. . - 

 Concha n<is. 7f?£d.. 

 CoiicJia ?tas. hif. --- 



Fig. 3 From a term fetus. Here a single fr 

 bordered by a dorsal and a ventral frontal furrow. 

 and the frontal furrows are continuous channels, 

 condition due to growth, i.e., whether the frontal 

 ethmoidale were discontinuous anlagen, cannot 

 series the condition is not common. 



//V7/ful fold or Cflffc/m 



^ Bulla eth. 



CoT/cI/a nas. s7ipre??>,a H 

 Co/fcha nas.si/pnwal 



ontal fold or concha presents, 

 The infundibulum ethmoidale 



Whether this is a secondary 

 furrows and the infundibulum 



bo said. According to my 



There are exceptions to this rule. Occasionally at birth the 

 genetic point for the sinus frontalis is obvious. Again, one 

 cannot be certain until the second or the third year. 



From the suprabullar furrow develop most of those cellulae 

 ethmoidales anterior which in time honeycomb the bulla ethmoi- 

 dalis. Rarely the suprabullar furrow seems to be the gen- 

 etic point for the sinus frontalis. This may be apparent only 

 and not the actual condition. The most dorsal of the frontal 

 pits and the suprabullar furrow are at times continuous channels 

 (fig. 2). This might lead to the interpretation that the sinus 

 frontalis developed from the suprabullar furrow, when in re- 

 ality it developed from a frontal pit (early anterior ethmoidal 

 cell). At times some of the bullar cells develop from occasionrJ 



THE AMERICAN .lOLRXAL OF .\X.'lTO-MV, VOL. 20, NO. 1 



