112 THE NASAL ACCESSORY SINUSES IN MAN 



formed in this way. In view of these facts we are inclined 

 to believe that if two pneumatization pouches were to ad- 

 vance into the maxilla the result would be a double maxillary 

 sinus, instead of the only remains being simply the dupli- 

 cated ostia. In rare instances double maxillary sinuses are 

 present, but we have found no report of a case in which both 

 of the ostia opened into the infundibulum. Double maxil- 

 lary sinuses will be considered later. 



The ostium maxillare accessorium (Figs. 27, 30, 33, and 

 48) is an opening which is sometimes found in the medial 

 wall of the sinus maxillaris, forming an additional communi- 

 cation with the meatus nasi medius. Such openings vary 

 from 0.5 to 15 mm. in diameter, and are most frequently 

 situated at a point 5 to 10 mm. above the superior border 

 of the concha inferior, at the junction of its posterior and 

 middle thirds. The majority of observers have found ac- 

 cessory ostia present in about 10 per cent, of adult cases. 

 Schaeffer, in 80 cases, found accessory ostia in 43 per cent, 

 of them. In my own series, 114 lateral nasal walls from cases 

 between four and twenty-four years of age show accessory 

 ostia in 15 per cent, of cases. The youngest specimen show- 

 ing an accessory ostium was from a child four years, three 

 months, and two days old; thus cases under four years of 

 age were excluded in estimating the frequency of its occur- 

 rence. Two accessory ostia (Fig. 48) were present in two 

 specimens. 



The ostium maxillare accessorium evidently has no em- 

 bryologic significance in its development; neither can it 

 be considered as a compensatory opening which has de- 

 veloped because of a deficiency in the size of the normal 

 ostium maxillare, for in no case showing the presence of an 



