54 THE NASAL ACCESSORY SINUSES IN MAN 



high up on the lateral nasal wall, then the cellulse frontales 

 are apt to be well developed. However, if the anterior 

 attachment of the processus uncinatus is more medial in 

 position and the anterosuperior attachment of the concha 

 media is situated lower on the lateral nasal wall, then the 

 recess is small, the cellulae frontales are apt to be deficient 

 in development, and there is usually a corresponding in- 

 crease in both the number and the extent of development of 

 the cellulae infundibulares. 



In some instances the infundibulum ethmoidale terminates 

 anteriorly as an expansion into a single cell. However, 

 there are usually two or three cellulse infundibulares present, 

 and in some instances in which the cellulae frontales were 

 poorly developed four were found. In 15.6 per cent, of 

 cases the sinus frontalis developed directly from the in- 

 fundibulum ethmoidale (Fig. 35) , in which class of cases there 

 were cells anterior and lateral to the ostium. The adult 

 cellulae infundibulares are usually bordered superiorly by 

 the frontal bone, and often the lateral extent is such that 

 they extend well into the supra-orbital plate. Not infre- 

 quently in specimens from adults and also from older chil- 

 dren one of the infundibular cells (Fig. 47) forms a projection 

 into the postero-inferior portion of the floor of the sinus 

 frontalis, termed by Logan Turner the bulla frontalis. 

 Observations on specimens showing the conditions present 

 during the developmental period indicate that the cell de- 

 veloped into such a position at an earlier period than that 

 at which the sinus frontalis reached so far in its lateral de- 

 velopment. Thus the developing sinus frontalis, as its 

 pneumatization extends laterally, passes around the superior 

 wall of the cell in a manner which makes the appearance, 



