THE ASDOMBK 917 



to the great cavity. The structures contained between these two layers are 

 to be noted. As the finger Ues in the foramen of Winslow the caudate lobe 

 of the Uver will be felt above it. It is possible for a hernia to occur through 

 this foramen. 



The relation of the duodenum to the peritoneum should next be attended 

 to. Certain peritoneal fossae are to be studied in the following order : ( 1 ) 

 the duodenal and duodeno-jejunal fossae ; (2) the peri-caecal fossae, namely, 

 ileo-colic, ileo-caecal, and retro-caecal ; and (3) the intersigmoid. The study of 

 the peritoneum in the adult having been concluded, the dissector should 

 attend to the condition of the peritoneum in the foetus. 



The dissection of the mesentery proper should now be proceeded with. 

 The great omentum, with the transverse colon, is to be raised and laid over the 

 costal margin, and the jejunum and ileum are to be carried over to the left side. 

 The dissector is to place portions of the mesentery successively upon a platter, 

 and remove the right or upper layer. The trunk of the superior mesenteric 

 artery is to be dissected beyond the point where it escapes from under cover of 

 the pancreas, and the superior mesenteric sympathetic plexus around it is to 

 be noted, as well as the superior mesenteric vein on its right side. About twelve 

 rami intestini tenuis are to be shown arising from the left side of the parent 

 trunk, and these are to be followed out to their primary, secondary, and at 

 least tertiary arches, attention being given at the same time to the accom- 

 panying sympathetic plexuses and veins. During this dissection the mesen- 

 teric glands are to be sho\vn, and an effort should be made to display the 

 lacteals, which enter the glands as afferent vessels, and emerge from them as 

 efferent vessels. 



The*right side of the superior mesenteric artery will be found to give off, in 

 order from above downwards, the inferior pancreatico-duodenal, middle colic, 

 right coUc, and Ueo - colic branches, but they should be followed out from 

 below upwards. The ileo-colic is to be shown dividing into a colic and an 

 ileo-caecal branch, the latter of which will be found to give off appendicular, 

 anterior caecal, posterior caecal, and ileal branches. The right coUc and middle 

 colic are to be shown, each dividing into two branches, the latter lying 

 between the two layers of the transverse meso-colon. Throughout this 

 dissection the tributaries of the superior mesenteric vein are to be noted, as 

 well as the offshoots from the superior mesenteric sj^mpathetic plexus. The 

 inferior pancreatico-duodenal artery should not be followed out at this stage. 



The jejunum and ileum are now to be carried over to the right side, and the 

 left branch of the middle colic artery is to be followed to its termination. 

 This will guide the dissector to the descending branch of the left cohc artery, 

 and, as he follows this down, he wiU readily expose the trunk of the inferior 

 mesenteric artery, arising from the aorta about li inches above the bifurcation. 

 In doing so, he is to note that the artery is behind the parietal peritoneum. It 

 will be found to give off a left colic branch, one, two, or three sigmoid branches, 

 and a superior hemorrhoidal branch. The inferior mesenteric sympathetic 

 plexus and ganglion, and the offshoots from the plexus should be noted. The 

 left colic and superior sigmoid arteries are to be followed to their distribution, 

 and the superior hemorrhoidal is to be shown crossing the left common iUac 

 vessels on its way to the pelvis, where it disappears between the two layers 

 of the pelvic meso-colon. The superior hemorrhoidal, sigmoid, and left colic 

 veins will be found to form the inferior mesenteric vein, which is to be followed 

 upwards on the left psoas magnus as high as the pancreas, care being taken 

 to show that it crosses the left spermatic artery and left renal vein. 



The intestines are now to be removed in the following manner : a double 

 ligature is to be placed upon the jejunum at its commencement, and another 

 double ligature at the point where the ihac colon passes into the pelvic colon. 

 The gut is then to be divided between each of these double ligatures, and the 

 jejunum and ileum are to be separated from the mesentery propxer by dividing 

 the latter with a knife, or clipping it with scissors. When this has been done, 

 the large intestine should be forcibly drawn out from its deep position, any 

 adhesions which it has formed being severed with a knife. The parts of 

 intestine left behind are (i ) the duodenum, and (2) the pelvic colon and rectum. 



I 



