Lateral Wall of the Cavum Nasi in Man. 675 



sinus maxillaris so far ventral as Zuckerkandl represents it to be 

 in Fig. 6, Taf. XI, of the above named work. What he labels 

 "^. m." in the latter figure is, I think, wholly infundibulum eth- 

 moidale, i.e., a frontal section of the superior and ventral portion 

 of it. I, however, think that we should speak of the sinus maxil- 

 laris as developing from the preexisting furrow (infundibulum 

 ethmoidale), and not consider the latter a part of the sinus max- 

 illaris. However, as stated before, it is difficult at times to draw 

 this distinction; especially so when the primitive sinus maxil- 

 laris is extensive and occupies the greater portion of the infun- 

 dibulum ethmoidale in its early pouching. 



The duplication of the primitive maxillary pouch, and the 

 extensive pouching that we occasionally have, is entirely in accord 

 with adult conditions — in that the adult ostium maxillare varies 

 from a small aperture to a long slit-like opening, while in other 

 cases the ostium is duplicated. In this connection I may be per- 

 mitted to quote briefly from an earlier paper: "I have found 

 the primitive maxillary pouch duplicated . . . This may 

 explain some of the duplications of the ostium maxillare of the 

 adult sinus. The two primary pouches may fuse distally, leaving 

 the two points of evagination as the ostia maxillaria of the adult 

 cavity. This embryonal condition in all probability explains 

 some of the cases in which the sinus maxillaris is divided into two 

 partly or wholly separate compartments by a vertical partition, 

 i.e., each pouch developing into an adult cavity independent of 

 its mate .... The great differences in the dimensions 

 of the adult ostium may be due to the coalescence of two or more 

 maxillary pouches; or the primitive pouching may have been 

 single but extensive." 



The early sinus maxillaris is for a time a slit-like cavity in the 

 lateral wall of the nose. It extends inferiorly into the recess 

 formed by the union of the cartilage of the lateral wall with that 

 of the concha nasalis inferior (fig. 18). By resorption (of car- 

 tilage) and growth (of the sac), the sinus ultimately breaks 

 through the cartilage in the position mentioned above (figs. 31 

 and 34). Its further extension into the body of the maxilla is 

 accomplished by the simultaneous growth of the sinus and the 



