The Sinus Maxillaris in Man. 363 
The anterior superior alveolar (dental) nerve was given off 
from the infraorbital nerve, proximal to the infraorbital foramen. 
It passed inferiorly in the alveolar canal of the anterior surface 
of the maxilla and took part in forming the superior dental plexus 
of nerves. From this plexus arose the superior dental nerves 
which supply the fangs of the teeth, the gums, and give numerous 
branches to the maxilla and the mucous membrane of the sinus 
maxillaris. 
I also observed—a very important condition—that in one case 
the anterior superior alveolar nerve came off’ from the infra- 
orbital nerve quite a distance proximal to the infraorbital fora- 
men. The nerve then passed through the inferior wall of the 
infraorbital canal and took a course diagonally across the sinus 
from the roof to its ventral wall. The nerve thus suspended 
freely in the cavity of the sinus maxillaris was surrounded merely 
with mucous membrane (fig. 31). 
CONCLUSIONS. 
1. The Anlage of the sinus maxillaris appears during the third 
month of fetal life as a minute epithelial sac evaginating and 
growing at first inferiorly, later more laterally, from the dorsal 
end of the primitive infundibulum ethmoidale. 
2. The primitive maxillary pouch may be duplicated. In 
some cases this may account for the duplication of the ostium 
maxillare of the adult sinus, i. e., the two pouches fusing distally, 
leaving the two points of evagination as the adult ostia. Other 
duplications of the ostium may develop in a way similar to that 
of the accessory ostium. 
3. The primitive ostium maxillare varies very much in its 
dimensions in different embryos. This is entirely in accord with 
adult conditions, since the ostium of the adult sinus has a great 
range of dimensions. 
4. Dentition seems to influence the size of the cavity but 
little. The age of the child and the size of the sinus apparently 
progress pari passu. 
5. The cavity enlarges by the simultaneous growth of the 
