DESCRIPTIVE ANATOMY OF THE TEETH. 143 



incisors are generally larger and stronger than the lower. 

 In the upper jaw the central incisors are larger than the lat- 

 eral ; while in the lower jaw the lateral incisors are larger than 

 the central. Each of the incisors has but a single root. The 

 special function of the incisor teeth is to divide the food as 

 it is taken into the mouth. The permanent incisors make 

 their appearance from the seventh to the eighth year. 



The canines are more conical and pointed than the in- 

 cisors, and have longer and larger roots, especially those in 

 the upper jaw. Their roots are single. They are used to 

 some extent, in connection with the incisors, in dividing the 

 food ; but have no prominent function in tearing the food, 

 as in the carnivora, in which they are extraordinarily de- 

 veloped. ' The permanent canines make their appearance 

 from the eleventh to the twelfth year. 



The bicuspid teeth are shorter and thicker than the 

 canines. Their opposed surfaces are rather broad and are 

 marked by two eminences. The upper bicuspids are some- 

 what larger than the lower. The roots are single, but in 

 the upper jaw are slightly bifurcated at their extremities. 

 They are used, with the true molars, in triturating the food. 

 The permanent bicuspids make their appearance from the 

 ninth to the tenth year. 



The molar teeth, called respectively counting from before 

 backward the first, second, and third molars, are the largest 

 of all, and are, par excellence, the teeth used in mastication. 

 Their form is that of a cube, rounded laterally, and provided 

 with four or five eminences on their opposed surfaces. The 

 first molars are the largest. They have generally three roots 

 in the upper jaw, and two in the lower ; although they some- 

 times have four and even five roots. The second molars are 

 but little smaller than the first, and resemble them in nearly 

 every particular. The third molars, called frequently the 

 wisdom-teeth, are much smaller than the others, and are by 

 no means so useful in mastication. In the upper jaw the 

 root is grooved or imperfectly divided into three branches ; 



