III. Endgut, the last segment of the intestinal canal, courses through the pelvic portion of the body cavity. From this short end-piece are developed: (1) The colon, sigmoid flexure and rectum; (2) the cloaca with the uro-genital sinus and the duct of the allantois.
PART I.
ANATOMY OF THE PERITONEUM AND ABDOMINAL CAVITY.
For the purpose of studying the adult human peritoneum it is in the first place absolutely necessary to obtain a correct appreciation of the disposition of the chief viscera within the abdominal cavity and of their mutual relations. In the second place the visceral vascular supply of the abdomen must be carefully considered in order to correctly appreciate certain important relations of the peritoneal membrane.
A review of the visceral contents of the abdomen shows that we have to deal chiefly with the divisions of the alimentary tract below the œsophagus and the structures directly derived from the same, as liver and pancreas, or associated topographically with the alimentary canal, as the spleen. Portions of the urinary and reproductive systems situated within the abdominal and pelvic cavities will also require consideration.
The digestive apparatus as a whole presents, in the first place, a segment designed to convey the food to the stomach, the œsophagus—supplemented in mammalia by the special apparatus of the mouth and pharynx, in which the food is mechanically prepared for digestion by chewing and mixed with the secretion of the salivary glands.
The digestive apparatus proper, succeeding to the œsophagus, is usually divisible into two sections differing in function and structure.
1. The STOMACH, a short sac-like dilatation, in which chiefly nitrogenous material is digested.