The intestinal canal may be divided into two parts, the small intestine and the large intestine (Fig. 1). The small intestine (intestinum tenue) is about seven to eight metres long, the first portion being called the duodenum, the second the jejunum, and the third the ileum. With the exception of the duodenum the small intestine lies for the most part inside the more fixed portion of the large intestine and is connected to the posterior abdominal wall by the mesentery. This broad membrane extends from above downward and from left to right, from the end of the duodenum above to the ileocaecal valve below, enclosing the jejunum and ileum along the whole of their extent.

The Intestine, as Seen from the Front after Removing the Omentum

Fig. 1. - The Intestine, as Seen from the Front after Removing the Omentum (Testut). 1, Abdominal wall; 2, wall of the thorax; 3, oesophagus; 3', cardia; 4, stomach; 4', pylorus; 5, duodenum; 6, pancreas; 7, liver; 8, gall bladder; 9, gastrohepatic ligament: 10, right kidney and its suprarenal capsule; 11. small intestine; 12, terminal portion of the ileum; 13, escnm; 13', its appendix; 14. ascending colon; 15, transverse coIon; 16, descending colon; 17, ileopelvic colon; 18, bladder; 19, parietal peritoneum; 20, spleen: 21. diaphragm: 22, thoracic aorta.