THE PERITONEUM 423 



(NoTE. The adult peritoneum will never be fully under- 

 stood until the student acquires a thorough knowledge of the 

 development of the intestinal canal in the embryo, and the 

 books on embryology should be carefully studied on this 

 subject.) 



The General Arrangement of the Peritoneum. Starting from 

 the anterior abdominal wall, in the median line, the peritoneum 

 passes around on the right side to invest completely the lower 

 part of the cecum and the vermiform appendix, but only parti- 

 ally investing the rest of the cecum, covering its front and sides, 

 the back part being very often uncovered. It partially invests 

 the entire ascending colon in a similar manner. Quite often, 

 however, the back part of the cecum is also covered by the 

 peritoneum, which thus forms a mesocecum. It now covers 

 the lower part of the front of the right kidney and the front 

 of the third portion of the duodenum, excepting a transverse 

 zone, passes thence to the spine, and forming the right side 

 of the mesentery invests the jejunum and ileum, and returns, 

 as the left layer of the mesentery to the spine, tl us completing 

 the structure. The peritoneum now crosse^ ^^c lower part 

 of the left kidney, invests the descending colon in a manner 

 similar to that on the right side, forms a long sigmoid meso- 

 colon, and returns to the front of the abdomen. 



Starting in the median line behind at the sacral angle we 

 may trace the peritoneum downward to invest completely the 

 rectum in its upper part and partially invest it in its second 

 portion, covering it in front, and laterally, and lower down, 

 only in front, and at a point about 6 to 8 cm. above the anus 

 leaves the gut altogether. It is then reflected on to the base 

 and upper part of the bladder in the male, forming the recto- 

 vesical pouch. This pouch presents on each side a fold, the 

 plica semilunaris. From the apex of the bladder it ascends, 

 investing the urachus and obliterated hypogastric artery on 

 each side. In the female it passes from the rectum to the upper 

 part of the vagina, forming the rectovaginal pouch (or cul-de- 

 sac of Douglas), which presents plicae semilunares similar to 

 those found in the rectovesical pouch in the male. It then 

 covers both surfaces of the uterus, and forms the broad liga- 

 ments, investing the Fallopian tubes to the fimbriated ends, 

 where it becomes continuous with their mucous membrane. 



Above, the peritoneum runs on the under surface of the 



