THE TOMER. 51 



back part of the upper border, overhanging the posterior 

 border. It is trilateral, compressed from side to side, and 

 presents for examination an anterior, posterior, and supe- 

 rior border, and two surfaces, the external and internal. 

 The posterior border is thin, irregular, and articulates 

 with the pterygoid process. The superior border is flat- 

 tened, and overhangs the superior meatus; it is slightly 

 roughened, and articulates with the sphenoidal turbinated 

 bone. The anterior border is concave, smooth, and 

 rounded, and forms the posterior boundary of the spheno- 

 palatine notch. The external surface is divided by a 

 longitudinal crest into an anterior non-articular and a 

 posterior articular, grooved surface, which assists in form- 

 ing the posterior palatine canal. Anterior to the ridge 

 the bone is smooth, and leads into the spheno-palatine 

 foramen. The internal surface is smooth, strongly con- 

 cave from above downward, and assists in forming the 

 superior meatus of the nose. Between the sphenoidal 

 and orbital processes is the spheno-palatine notch or 

 foramen; it is oval in form, its long axis being almost 

 vertical in the articulated skull. Its boundary anteriorly 

 is smooth, broad, and formed by the posterior inferior 

 border of the orbital process. Posteriorly, the border 

 is . sharp ; small spiculse or spines of bone sometimes 

 project from the circumference, subdividing it. This 

 notch is converted into a foramen by the sphenoidal 

 turbinated bone. It transmits the spheno-palatine vessels 

 and nerves. 



The palate bones develop from a single centre, which 

 appears at the external border of the horizontal plate 

 about the third month. 



THE VOMER. 



The vomer is a flat, translucent, quadrilateral bone, 

 which articulates posteriorly with the rostrum of the 



