THE BONES OF THE HEAD lOi 



the intervening space is partitioned off into alveoli or sockets by 

 septa which pass between the two plates. The number of alveoli 

 in the adult bone is as a rule eight, and they gradually narrow 

 towards their upper or deep ends, where they are perforated by 

 foramina for the ner\'es and arteries of the teeth. They lodge the 

 roots of the teeth, which, in order from the middle line outwards 

 and backwards, are as follows : central incisor, lateral incisor, 

 canine, first bicuspid, second bicuspid, and first, second, and third 

 molars. The alveoli correspond in shape with the roots of the 

 teeth, the canine being the deepest. The outer surface of the 

 alveolar border, over the extent of the three molar sockets, gives 

 origin to fibres of the buccinator. 



C The palatal process is situated on the internal surface of the 

 body, from which it projects horizontally inwards, and, with its 

 fellow, it forms three-fourths of the hard palate, i It is quadrilateral, 

 and presents two surfaces and four borders.''^he superior surface 

 forms three-fourths of the floor of the nasal fossa, and is smooth, 

 concave, and covered in the recent state by the nasal mucous 

 membrane. The inferior surface forms a part of the hard palate, 

 and is rough, arched, and covered in the recent state by the buccal 

 mucous membrane. It presents several depressions for the palatal 

 mucous glands, and is perforated by several nutrient foramina. 

 Laterally it is marked by a groove, directed from behind forwards, 

 for the nerv^e and artery which reach the hard palate through the 

 posterior palatine canal. The posterior border stops short of the 

 back part of the alveolar border, and is short and serrated for 

 the horizontal plate of the palate bone. The anterior border, 

 superiorly, forms the lower part of the nasal notch. The external 

 border is attached to the body. The internal or mesial border 

 is faintly serrated, and articulates with its fellow. At the 

 place of meeting it is elevated into a ridge, forming, with that 

 of its feUow, the nasal crest, which is grooved to receive the lower 

 border of the vomer. This mesial ridge becomes prominent in 

 front, where it forms the incisor crest, which is projected to 

 constitute, with its fellow, the anterior nasal spine. It supports 

 the septal nasal cartilage, and the anterior extremity of the vomer 

 lies behind it. 



Close to the outer side of the incisor crest the palatal 

 process is pierced by an opening leading into a canal, which is 

 bounded internally by a thin plate of bone, and descends to the 

 front part of the hard palate, being ultimately converted into a 

 groove, due to its inner thin wall becoming deficient. This passage 

 is variously known as the incisor or naso-palatine canal, or canal 

 of Stensen (Steno), and the two canals, right and left, in the 

 articulated condition form interiorly a large orifice, called the 

 anterior palatine fossa. This fossa, which is somewhat diamond- 

 shaped, is situated in the middle line of the hard palate, behind 

 the central incisor teeth. On looking into it from below four 

 foramina are seen, two of which are placed in the middle line, 



