VISCERAL ANATOMY. 



What is a Viscus ? Viscus, gen, visceris, pi. viscera, is a term which is 

 applied to any internal organ of the body. The Viscera are the organs con- 

 tained in the three great cavities cranium, thorax and abdomen with their 

 appendages. Of these the Heart and Brain have been described, with the 

 circulatory and nervous systems respectively. [See pp. 99, 120; also the 

 COMPEND OF PHYSIOLOGY in this series.] 



THE DIGESTIVE ORGANS. 



What is the Alimentary Canal ? A musculo-membranous tube, from 25 

 to 30 feet in length, extending from the mouth to the anus, lined throughout 

 with mucous membrane, furnished with several accessory organs, and perform- 

 ing the functions of ingestion, digestion, and egestion. 



Name its Subdivisions. They are the Mouth, Pharynx, (Esophagus, 

 Stomach, Small Intestine (duodenum, jejunum and ileum) and Large Intestine 

 (caecum, colon and rectum). The first three lie above the diaphragm, the rest 

 below it. 



Name the Accessory Organs of Digestion. They are the Teeth, 

 Salivary glands (parotid, sub- maxillary, sub-lingual), Liver, Pancreas and 

 Spleen. 



THE TEETH. 



What are the Teeth ? They are 32 organs of digestion (20 being tempo- 

 rary, or milk-teeth), situated one-half in each jaw, imbedded in the alveolar 

 processes, and partly surrounded by the Gums, which are composed of fibrous 

 tissue and covered with mucous membrane. In each half of each jaw there 

 are 



Temporary Teeth (5) 2 Incisors, I Canine, 2 Milk-molars. 



Permanent Teeth (8) 2 Incisors, I Canine, 2 Bicuspids, 3 Molars. 



What are their General Characteristics ? Each tooth presents a 

 Crown, or Body, the part seen projecting above the gum. 

 Neck, the constricted portion between the crown and the fang. 

 Fang, or Root, imbedded in the alveolus ; and surrounded by the periodental 



membrane or periosteum lining the alveolus. 



141 



