THE ALVEOLI. 105 



side of the jaw, and one on the internal, with transverse bony 

 laminae passing between them. On the side of the cavity 

 which they form, their substance is loose and cellular ; on their 

 outer side, like other bones, they are smooth and compact. 

 — The transverse processes, are rather more prominent than the 

 lateral part of the parietes, corresponding in this respect inversely 

 with the line of enamel on the teeth. 



— The enamel terminates on the neck of the teeth a little above 

 the level of the sockets, leaving a small space on the bony part 

 of the neck round which the gum is attached. 

 — The alveoli, terminate in as many hollow processes, as there 

 are fangs to the teeth which they lodge : and at the bottom of 

 each of these processes there are one or more minute foramina, 

 for the transmission of vessels and nerves to the internal mem- 

 brane and pulp of the teeth. 



— The mode of articulation of the teeth in the sockets is called 

 gomphosis ; even in their perfect state, the teeth are slightly 

 movable in the socket, of which dental surgeons, occasionally 

 take advantage, in altering the direction of the teeth, by 

 mechanical means. The firmness of the articulation, depends 

 upon the adaptation in size and shape of the sockets to the 

 fangs, on the gum which surrounds the neck, of the periosteum 

 of the sockets which is continuous with that of the fangs, and 

 of the vessels and nerves which enter into the foramina of the 

 fangs. 



The teeth of different kinds differ greatly from each other, in 

 form and size. 



The body of the incisores is broad, with two flat surfaces, 

 one anterior and the other posterior ; the anterior surface is 

 rather convex and the posterior concave ; they meet in a sharp 

 cutting edge. At this edge the tooth is thinnest and broadest; 

 it gradually becomes thicker and narrower, as it is nearer the 

 neck. The enamel continues farther down on the anterior and 

 posterior surfaces than on the sides. 



The incisores of the upper jaw are broader than those of the 

 lower ; especially the two internal incisores. 



The cus])idati are longer than any other teeth, and are thicker 



