258 



DIGESTION. 



tinuous, and is also much wider than its continuation, the jejunum. It presents a curve, 

 which is ordinarily described by anatomists as consisting of three portions. The first, 

 called the hepatic or ascending portion, is about two inches in length. This is much less 

 firmly fixed by its peritoneal attachment than the other portions and is nearly covered 

 by the serous membrane. Its direction is outward, backward, and slightly upward. 

 Turning downward, and a little inward, it merges into the second, called the descending 



FIG. 63. Stomach, liver, small intestine, etc. (Sappey.) 



1, inferior surface of the lirer; 2, round ligament of tlie liver; 8, gall-bladder; 4, superior surface of the 

 right lobe of the liver ; 5, diaphragm; 6, lower portion of the oesophagus; 7, stomach; 8, gastro-liepatic omen- 

 turn; 9, spleen; 10, gastro-spJenic omentum ; 11, duodenum; 12, 12, small intestine; 13, cacum; 14, 

 appendix vermiformis ; 15, 15, transverse colon ; 16, sigmoid flexure of the colon ; 17, urinary bladder. 



or vertical portion, the length of which is about three inches. This is covered with 

 peritoneum only on its anterior surface and is somewhat more firmly attached than the 

 ascending portion. The intestine then makes a second bend, and the third or the trans- 

 verse portion is horizontal in its course, passing across the spine to the left hypochon- 

 drium. This portion is about five inches in length. It is narrower than the others, is 

 but partially covered by peritoneum, and is more firmly bound down than any other part 

 of the small intestine. 



The coats of the duodenum, like those of the other divisions of the intestinal tube, are 

 three in number. Commencing externally, we have the serous, or-pfiritoneal coat, which 

 has already been described. The middle, or muscular coat is composed of the involuntary, 

 or unstriped muscular fibres, such as exist in the stomach, arranged in two layers. The 

 external, longitudinal layer is not very thick, and the direction of its fibres can be made 



