VISCERAL ANATOMY. 125 



Muscular. Three layers, external, over right sac and also left 

 one; middle, circular over whole organ, aggregated at the pyloric 

 orifice to form the pyloric valve; internal, looped around left sac. 



Mucous. This is thrown into folds in the right, but not in the 

 left sac. It has a muscular layer, the muscularis mucosa, and is 

 covered with flattened epithelium in the left and cylindrical in the 

 right sac. 



Glands. 



Infrequent on left side and like those of oesophagus. Common 

 on right sac, and are of two varieties. 



(a] Peptic, with a narrow neck opening into two or three cul- 

 de-sacs, lined with rounded epithelium at the periphery and 

 small cells next to the lumen. The neck is lined with cylindrical 

 cells. 



(b) Mucous, similar in structure, but the whole gland is lined 

 with cylindrical epithelium. 



Blood Supply. Gastric, splenic, pyloric, cesophageal, right and 

 left gastro-epiploic vessels. 



Nerves. Tenth and solar plexus. 



INTESTINES. 



The terminal portion of the alimentary system, beginning at the 

 pylorus, ending at the anus by the rectum. It is a narrowed tube, 

 twisted and curved upon itself, and divided into small and large 

 divisions. Their entire length is about 98 feet 72 feet for the 

 small and 26 for the large. 



SMALL INTESTINES. 



These begin at the pylorus, form a loop over the base of the 

 caecum, turn transversely to the left, then form numerous folds, 

 being suspended by a process of peritoneum, the mesentery, finally 

 terminating in the caecum at the right hypochondrium. 



Length, 24 yards; diameter, i-i j inches. 



Divisions. Duodenum, the first curved portion. 

 Jejunum (empty), the greater part. 

 Ileum (twisted), the terminal portion. 



Coats, from without inward, are 



Serous, from peritoneum, covering all the small intestine com- 

 pletely, except a portion of the duodenum. 



