252 THE ORGANS OF DIGESTION 



The alimentary canal consists of the following: 



Mouth. fDuodenum. 



Pharynx. Small Intestine j Jejunum. 

 Esophagus. Uleum. 



Stomach . Cecum . 



Large Intestine olon - 

 Rectum. 



Anal canal. 



THE MOUTH, ORAL OR BUCCAL CAVITY 



The mouth is the upper part of the alimentary canal. 

 It is bounded by the lips, cheeks, tongue, hard and 

 soft palate, alveolar processes of both jaws, with 

 their contained teeth, and opens behind, through the 

 isthmus faucium, into the pharynx. It is lined by 

 mucous membrane continuous in front with the skin, 

 behind with that of the fauces, its epithelium being 

 stratified. 



The Teeth. The teeth in the human subject are 

 erupted in two sets, a temporary or deciduous, or milk 

 teeth, and a permanent or succedaneous set. The 

 former are 20 in number, 10 in each jaw; the latter, 

 32, 16 each above and below. Each tooth is made 

 up of three parts: the root, consisting of one or more 

 fangs, contained in the alveolus; the crown or body, 

 above the gum; and the neck, between the two. The 

 alveolar periosteum is reflected on to the fang as far 

 as the neck. 



The twenty temporary teeth are divided into 4 inci- 

 sors, 2 canines, and 4 molars above and below. The 32 

 permanent teeth are : 4 incisors, 2 canines, 4 bicuspids, 

 and 6 molars in each jaw. The temporary teeth are 

 similar to but smaller than the permanent; of the 

 temporary molars, the hinder one is the largest of 



