The Sinus Maxillaris in Man. 319 
a ridge appears immediately inferior to the point of maxillary 
evagination. This ridge is the Anlage of the processus uncinatus 
and, as said before, will be considered, merely for the sake of 
description, as the descending crus of the naso-turbinal. It will 
be recalled that Killian terms the latter two structures, ‘‘die 
M.N.M C.N 
4s AS: 
Le. M. N.M 
O. M 
S. M. 
M. N. 1 Ps 
Fie. 2 (X10). Drawing of a reconstruction of portion of the right nasal cavity; 
including the meatus, infundibulum ethmoidale, and the sinus maxillaris. Only 
that portion of the nasal cavity necessary to include the sinus maxillaris and its 
relations is shown. : 
Compare the size of the ostium maxillare with the corresponding aperture 
in fig. 3. 
The model was reconstructed from the nose of an embryo aged 105 days. It 
must be remembered that the drawing represents cavity and is, therefore, a 
negative. 
M. N. M., M. N. L, =meatus nasi, medius et inferior; I. E., = infundibulum 
ethmoidale; C.N., = cavum nasi; H. S., = hiatus semilunaris; O. M., = ostium 
maxillare; S. M., =sinus maxillaris. 
appear, and in some instances it is impossible to say whether the pouching of the 
mucous membrane, or the formation of the ridge is first. It may, however, be said 
that both structures are more or less dependent upon each other in establishing 
Anlagen. 
