322 



MAMMALIAN ANATOMY 



parallel to it. The anterior border articulates throughout its length 

 with the posterior edge of the horizontal plate of the maxillary bone. 

 The outer border begins at the back of the maxillary process of the 

 vertical plate, and runs inward and forward, then backward and 

 inward. It is rounded, and forms also the lower border of the vertical 

 plate. The lower surface of the horizontal plate is smooth, and some- 

 what elevated at its middle in an antero-posterior line. Near the 

 anterior border, and sometimes within it at some distance from the 



FIG. 250. 



With Lachrymal. 



With Opposite Palatine. 

 Horizontal Plate. 



One-half Posterior Nasal Spine 

 With Vomer and Presphejioid. 



With Palatine Plate of Maxillary. 



With Tuberosity of Maxillary. 



Opening of Posterior Palatine Canal. 

 Posterior Nares. 

 Vertical Plate. 



With Pterygoid. 

 LEFT PALATINE BONE, LOWER ASPECT. 



median border, is a well-marked foramen, the palatal opening of the 

 posterior palatine canal. There are, as a rule, several smaller foramina 

 behind the principal one and external to it. The lower surface is 

 covered by the mucous membrane of the mouth. 



The upper surface of the horizontal plate (Fig. 252) has the same 

 general shape as the lower surface. It is not so wide, however, inas- 

 much as the vertical plate, the base whereof is thick in front, springs 

 from its outer border. It is slightly concave from side to side, and 

 convex from before backward. The anterior end of the inner border 

 is sometimes elevated, and gives rise with the bone of the opposite side 

 to a short crest which articulates with the vomer. The upper surface 

 forms the floor of the back of the nasal chamber and of the posterior 

 narial canal (Fig. 269). 



The Vertical Plate may be said to consist of three parts : an 

 outer anterior hooked maxillary process ; a high anterior and upper 



