THE SINUS FRONTALIS 



137 





S.frcm-L 



Ost.fron.-t 

 el.lrifun.d: 



el.b.et-K. 



Cel.etK.post. 



FIG. 49. SPECIMEN, EIGHTEEN YEARS, ELEVEN MONTHS, AND TEN DAYS OLD. 



(Series D, No. 85.) 



Lateral view of the frontal, ethmoidal, maxillary, and a portion of the sphe- 

 noidal areas. Sinus frontalis developed from an infundibular cell. Note 

 that the ostium frontale is not in the most inferior portion of the floor of the 

 sinus. Cel.b.eth., Cellulse bullse ethmoidales; Cel.eth.post., cellulae ethmoidales 

 posterior; Ost.sph., ostium sphenoidale; S.sph., sinus sphenoidalis; A. car. int., 

 arteria carotis interna; N.abduc., nervus abducens; N.max., nervus maxil- 

 laris; Tub.aud., tuba auditiva (Eustachii); S.max., sinus maxillaris; 1, 

 probe through ostium maxillare; Duct.na.lacr., ductus nasolacrimalis; Cel. 

 infund.j cellula infundibularis; Ost.front., ostium frontale; S.front., sinus 

 frontalis. 



