362 PRACTICAL ANATOMY. 



Table of Eruption of the Permanent Teeth. 



First molars, 5 to 7 years. 



Central incisors, . . . 6 to 8 " 



Lateral incisors, . . . 7 to 9 " 



First bicuspid, . . . 9 to 10 " 



Second bicuspid, . . . . 10 to 11 " 



Lower cuspids, . . . . 10 to 12 " 



Second molars, . . . . 12 to 14 " 



Upper canines, . . . . 13 to 15 " 



Wisdom, . . . . . 17 to 45 " 



The teeth of the lower jaw, as a rule, precede the 

 upper by a few months. 



Method of Eruption. When the enamel is com- 

 pletely formed and the calcification of the other tissues 

 of the tooth is sufficiently advanced to enable it to bear 

 the pressure to which it is to be afterward subjected, its 

 eruption takes place, the tooth making its way through 

 the gum, which is absorbed by the pressure of the crown 

 against it. The tooth itself is advanced by the increas- 

 ing size of the root. At the same time the septa between 

 the dental sacs, at first fibrous in structure, ossify and 

 constitute the alveoli. While the teeth are in place they 

 are firmly attached to the peridental membrane, and on 

 removal of the tooth the alveoli finally become absorbed. 



THE SALIVARY GLANDS. 



The salivary glands consist of three pairs the parotid, 

 submaxillary, and sublingual and numerous simple fol- 

 licles imbedded in the mucous membrane of the mouth. 

 The parotid gland is situated in front and below the ear, 

 wedged in between the mastoid portion of the temporal 

 bone and the posterior border of the ram us of the lower 

 jaw; it is irregularly lobulated, grayish in color, and 

 formed of lobes which are made up of lobules, and these 

 are composed of frequent branching tubules which dilate 



