ABDOMEN. 



239 



back smooth, moist, glistening, and attached; you will sec it covering every 

 organ in the abdominal cavity partially or completely. If by force of circum- 

 stance organs lose all or some' of their peritoneal covering, this is no fault of the 

 peritoneum. Remember, the primitive relation of every organ to peritoneum is 

 behind partially or completely covered thereby. (Figs. 167 and 168.) 



Figure 167 shows aorta giving three branches to three organs. The organ in 

 the centre is for practical purposes completely invested by peritoneum. Between 

 the two parts of the peritoneal fold is (l) The organ ; (2) the vessels that take 

 blood to and from the organ ; (3) the nerves that innervate the organ ; (4) the 



VISCERAL LAYER OF PERITONEUM 



PERITONEAL CAVITY 



PARIETAL LAYER OF PERITONEUM 



KIDNEY AND ITS RENAL VESSELS 



MESENTERY 



Tht aorta 



FIG. 167. SHOWING PARTIAL AND COMPLETE INVESTMENT OF ORGANS BY PERITONEUM. 



lymphatics that scavenger the organ. The organ has only one place where it is 

 accessible only one communication with the wall. 



Examine the cadaver, take up a portion of the small intestine, find the 

 superior mesenteric artery, and trace it down between its two parts of the peritoneal 

 folds. Now, with your forceps, make a rent in one side of the mesentery, examine, 

 and find an artery, a vein, nerves, glands, and fat, as represented in figure 166. 



4. Explain implantation of meso-structures. 



That part of the alimentary canal which remained in its original mid-line of 

 the body as the greater part of the small intestine and rectum may be said to 

 be an example of primitive implantation ; those parts which contracted adhesions 



PARIETAL LAYER OF PERITONEUM 



PERITONEAL CAVITY 



T/ie aorta 



FIG. 168. SHOWING RETRO-PERITONEAL LOCALITY. 



to localities other than the mid-line, may be said to be examples of acquired 

 implantation. The colon and duodenum are examples of this latter variety. 



5. From ii'/inf source does flic peritoneum dcrire its blood-supply f 



It will be presently seen that the abdominal aorta has parietal branches and vis- 

 ceral branches. The parietal branches, as the lumbar and phrenics, supply the peri- 

 toneum covering these walls ; the visceral branches supply the peritoneum cover- 

 ing the organs. 1'eriti meal arteries are, then, of two classes visceral and parietal. 



6. Explain peritoneal investment of organs. 



