THE TEETH. 



99 



the other moves out of the glenoid cavity, upon the tubercle : 

 but these important motions can be better understood, after the 

 muscles, and the articulation with the temporal bone, in its recent 

 state, have been described. 



Fig. 23. 



Of the Teeth. 



In the adult, when the teeth are perfect, there are sixteen in 

 each jaw, and those in corresponding situations, on the opposite 

 sides, resemble each other exactly. 



They are of four kinds, viz. incisores, or the fore teeth ; cuspi- 

 dati, or the canine ; bicuspides, or the small grinders ; and 

 molares, or the large grinders. 



On each side of the jaw, supposing it divided in the middle 

 there are two incisores, one cuspidatus, two bicuspides, and three 

 molares. They occur in the order in which they have been 

 named, beginning at the middle of the jaw, as in the above 

 figure. 



Each tooth is divided into two parts, viz. the body, or that 

 portion which is bare, and projects beyond the alveoli and gums ; 

 and the root, which is lodged in the socket. The boundary 

 between these parts, which is embraced by the gums, is called 

 the neck of the tooth. 



The body and roots consist of a peculiar kind of bone (dentine) 

 which is more firm and hard than the substance of the other 

 bones ; but all the surface of the body, which projects beyond 



