1106 



THE DIGESTIVE SYSTEM. 



III. Accessory Digestive Glands. The largest of these is the liver (hepar), 

 which occupies the upper and right portion of the abdominal cavity, immediately 

 below the diaphragm, and its secretion the bile is conveyed into the duodenum by 

 the bile duct (ductus choledochus). The pancreas, next in size, lies across the front of 

 the vertebral column, with its right end or head resting in the concavity of the 

 duodenum, into which its secretion flows through the pancreatic duct. The salivary 

 glands consist mainly of three large paired glands, parotid, submaxillary, and sub- 

 lingual (glandula parotis, submaxillaris, and sublingualis), and their ducts, which 

 convey the saliva, open into the mouth. The saliva is a mechanical lubricant, 

 which facilitates swallowing and the movements of the tongue in speaking and 

 masticating, and also plays an important part in the chemical processes of 

 digestion. 



CAVUM OEIS. 



The philtrnm 



Raphe of palate 



Uvula 



palatine arch 



1. Parts. Rima oris, vestibulum oris, cavum oris proprium. 



2. Boundaries. 1. Labia oris their structure. 



2. Buccae their structure. 



3. Palatum (palatum durum, palatum molle) arrangement and structure. 



4. Isthmus faucium. 



3. Structures found in the Mouth. Gringivae, gums. 



Dentes, teeth. 

 Lingua, tongue. 



4. G-landulse oris. Buccal and salivary glands. 



The mouth is the upper expanded portion which forms the first division 

 of the alimentary canal. It lies between the maxillae and mandible, bounded ex- 

 ternally by the lips and the cheeks, and roofed in by the palate. It contains the 

 teeth and greater part of the tongue ; and the ducts of the salivary glands open 



into it. The cavity is divisible into 

 two portions, the vestibule and the 

 cavity proper of the mouth. These 

 are separated from one another by the 

 alveolar ridges, gums, and teeth of the 

 maxillae and mandible. The cavity of 

 the m0 uth narrows at the back to a 



. TIT i 



slight constriction, marked by a vertical 

 fold on each side, called the arcus 

 glosso-palatinus (O.T. anterior pillar 

 of the fauces), and between them the 

 cavity of the mouth is continuous with 

 ^at of the pharynx. 



Rima Oris. The aperture of the 

 mouth is bounded above and below by 

 the corresponding lips, which, by their 

 junction at the sides, form the labial 

 commissures. In a state of rest, with 

 the lips in apposition, the rima appears 

 as a slightly curved line, corresponding 

 in length to the interval between the 

 first premolar teeth, and in level to 

 a line drawn across just below the 



It also shows the two palatine arches, and the pharyngo- middle of the upper inClSOr crOWDS. 

 nasal isthmus, through which the naso-pharynx, above, The shape of the rima varies with 

 communicates with the oral portion of the pharynx, eve ry movement of the lips, from the 



resting linear form, curved like the 



conventional bow, to a circular or oval shape when the mouth is widely open, 

 or the "pursed-up" condition produced by the contraction of the orbicularis oris 

 muscle. 



Vestibulum Oris. The vestibule of the mouth lies immediately internal 1 to the 



fonsii ine 



Ton ue 



FIG. 874. OPEN MOUTH SHOWING PALATE AND 

 PALATINE TONSILS. 



