THE ORGANS OF DIGESTION. 



THE Apparatus for the Digestion of the Food (apparatus digestorius) consists 

 of the alimentary canal and of certain accessory organs. 



The alimentary canal is a rausculomembranous tube, about thirty feet, or nine 

 meters, in length, extending from the mouth to the anus, and lined throughout the 

 entire extent by mucous membrane. It has received different names in the various 

 parts of its course; at its commencement, the mouth, we find provision made for 

 the mechanical division of the food (mastication), and for its admixture with a fluid 

 secreted by the salivary glands (insalivation'); beyond this are the pharynx and 

 the oesophagus, the organs which convey the food (deglutition) into that part of 

 the alimentary canal, the stomach, in which the principal chemical changes occur, 

 and in which the reduction and solution of the food take place; in the small intes- 

 tine the nutritive principles of the food are separated, by its admixture with the 

 bile, pancreatic and intestinal fluids, from that portion which passes into the 

 large intestine, most of which is expelled from the system through the rectum and 

 anal canal. 



Alimentary Canal. 



I Duodenum. 



Mouth. Small intestine | Jejunum. 



Pharynx. ' Ileum. 



(Esophagus. I Cecum. 



Stomach - Large intestine olon. 



I Rectum. 



I Anal canal. 



Accessory Organs. 

 Teeth. 

 Tongue. 



f Parotid. Liver. 



Salivary glands \ Submaxillary. Pancreas. 



( Sublingual. 



THE MOUTH, ORAL OR BUCCAL CAVITY (CAVUM ORIS). 



The mouth is placed at the commencement of the alimentary canal; it is a 

 nearly oval-shaped cavity, in which the mastication and insalivation of the food 

 take place (Figs. 913 and 914). 



The aperture of the mouth (rima or is) is bounded by the lips. The angle of the 

 mouth (angulus oris) is formed on each side by the meeting of the upper and 

 lower lips (commissura labiorum). When at rest with the lips in contact, the rima 

 is a slightly curved line. Every movement which the lips make alters the shape 

 of the rima. When the mouth is closed the floor and roof are usually in contact 

 and its sides are approximated to the dental arches. The mouth consists of two 

 parts an outer, smaller portion, the vestibule, and an inner, larger part, the cavity 

 proper of the mouth. 



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