THE SINUS MAXILLARIS 131 



folds of any of the above-mentioned varieties probably 

 assume an important role from a practical viewpoint, only 

 in the presence of suppurative conditions within the sinus, 

 when, the recesses or pockets make the thorough cleansing of 

 the cavity more difficult. 



A few cases have been reported in which there was a com- 

 plete osseous septum dividing the sinus maxillaris into two 

 distinct cavities, each having its independent ostium com- 

 municating with the nasal fossa. According to Zuckerkandl, 

 the anterior sinus, in such cases, communicates with the 

 infundibulum ethmoidale through the normal ostium maxil- 

 lare, while the posterior sinus communicates with the 

 meatus superior. Thus it is seen that the posterior sinus 

 is in reality an aberrant posterior ethmoidal cell which in- 

 vaded the body of the maxilla and there developed exten- 

 sively. In this series no such development was found suffi- 

 ciently extensive to justify terming it a double sinus; but 

 in one instance (Fig. 50) such an aberrant posterior ethmoidal 

 cell is shown, and indicates the manner in which greater 

 pneumatization by such a cell would produce a double 

 maxillary sinus. 



