THE SINUS MAXILLARIS 113 



accessory ostium was the normal ostium found to be smaller 

 than the average for the given age. The process of its de- 

 velopment is apparently a progressive thinning of the medial 

 wall of the sinus at a point where the wall is naturally thin, 

 and where there is no osseous lamina between the mucosa 

 lining the sinus and that lining the meatus medius, the thin- 

 ning continuing until an actual opening through the mem- 

 branes occurs. In a great majority of the cases in which 

 accessory ostia were found there were pathologic processes 

 present to give evidence of lowered vitality in those im- 

 mediate areas, and in several instances the situation of 

 mucous cysts was such as to interfere with the normal circu- 

 lation of the medial sinus wall. 



In 76 per cent, of cases showing accessory ostia there were 

 mucous cysts (retention cysts) in the mucosa lining the 

 medial walls of the sinus maxillares (Figs. 30 and 33) . The 

 cysts varied from 0.5 to 9 mm. in diameter. In 19 per cent, 

 of cases the mucosa was distinctly granular in appearance, 

 but showed no cysts. In the remaining 5 per cent, of cases 

 the surrounding mucosa was apparently normal. 



The cases in this series suggest the possibility of pulmonary 

 tuberculosis having some influence upon the frequency of 

 the occurrence of the ostia accessoria, but we do not regard 

 the series as sufficiently large to establish this relationship 

 as a definite fact. However, we submit the observation 

 that in 114 lateral nasal walls from cases between four and 

 twenty-two years of age, 15 per cent, showed the presence 

 of accessory ostia. Of the 114 specimens, 42 per cent, were 

 from patients who had died from pulmonary tuberculosis. 

 In the specimens from tuberculous cases, 37.5 per cent, had 



