BONES OF THE FACE. 201 



more, as well as presenting the most dependent position of 

 this sinus, though the antrum may be entered from the 

 alveolus of either the second or first bicuspis, but the direc- 

 tion would have to be obliquely backwards. 



The alveoli of all the molar teeth present the triple divis- 

 ion for its roots, which latter sometimes very much diverge, 

 and then again, on the contrary, greatly converge, so much 

 as sometimes to present the appearance of a single root. 

 Either too great divergence or convergence of the roots 

 offers difficulties to extraction, and especially so when a 

 portion of the alveolus is embraced. 



The posterior edge of the palatine process is thin and 

 serrated to join the palate bone internally it is thick where 

 it unites with its fellow and at the anterior part of this 

 union is the anterior palatine canal, which opens superiorly 

 into the nostrils by two foramina, and inferiorly on the 

 mouth by one, the foramen incisivum. 



At the place of junction of the palatine processes, the 

 upper edge in the nares is raised, and called the nasal crest, 

 which receives the inferior border of the vomer. This crest 

 projects forwards and forms the nasal spine, between which 

 and the nasal process, the bone is rounded and concave, 

 forming the anterior nares. 



The internal or nasal surface. The nasal surface presents 

 a very large opening situated between the middle and lower 

 turbinated bones, and leading into a cavity called the 

 antrum Higlimorianum, or maxillary sinus. This sinus is 

 of a triangular or pyramidal shape, the base looking to the 

 nose, the apex to the malar process. It is bounded above 

 by the orbitar process of the superior maxillary bone, form- 

 ing its roof, below by that portion of the alveolar arch cor- 

 responding to the first and second molar teeth, constituting 

 the floor ; in front by the canine fossa, and behind by the 

 tuberosity. Its shape and size vary much in different 

 bones. It is lined by the pituitary membrane of the nose. 

 Its opening in the natural skeleton is much contracted by 

 the ethmoid and lachrymal bones above and in front, by the 

 inferior spongy below, and the palate bone behind. This 



