286 ABDOMEN 



peritoneum on the anterior and posterior surfaces of the 

 latter, they become continuous with the two layers of the trans- 

 verse meso-colon, which attaches the transverse colon to the 

 structures lying on the posterior wall of the abdomen. The 

 contents of the greater omentum are (i) a portion of the 

 cavity of the omental bursa which separates the anterior two 

 layers from the posterior two layers; (2) between the anterior 

 two layers, along the lower border of the stomach, the right 

 and left gastro-epiploic blood vessels and their branches, with 

 lymph vessels and small lymph glands; (3) between the posterior 

 two layers lie small branches of the middle colic artery, which 

 have crossed the surfaces of the transverse colon and are de- 

 scending into the lower border of the greater omentum, where, 

 in very favourable circumstances, their anastomoses with de- 

 scending branches of the gastro-epiploic arteries may be seen. 



Dissection. Take away the more superficial of the anterior 

 two layers of the greater omentum along the lower border of 

 the stomach and expose the gastro-epiploic arteries. Trace 

 the left artery to the left to the gastro-splenic ligament, and note 

 that it passes forwards to the stomach between the two layers 

 of that ligament. At a later stage it will be followed to the 

 splenic artery, from which it springs. Trace the right artery 

 to the right to the point where it springs from the gastro- 

 duodenal artery at the lower border of the first part of the 

 duodenum. 



Remove the anterior two layers of the greater omentum (see 

 Fig. 132). This part of the dissection is not always easy to 

 accomplish, for not uncommonly the posterior of the anterior 

 two layers is fused with the anterior of the posterior two layers, 

 the lower part of the cavity of the omental bursa being ob- 

 literated ; but if the dissector commences near the left end of 

 the lower border of the stomach he will usually find the cavity 

 persistent. First, he should pull the lower border of the stomach 

 forwards, and cut through the anterior two layers of the omentum 

 below the left gastro-epiploic artery ; next, he should introduce 

 his fingers through the opening and gradually separate the 

 anterior two layers from the posterior two layers ; then he must 

 enlarge the opening, and, after separating the anterior from 

 the posterior layers as far as possible, he must cut away the 

 anterior layers. After that portion of the dissection is completed 

 he must introduce one hand into the cavity of the omental 

 bursa and he will find that he can pass it upwards behind the 

 stomach and behind the posterior surface of the lesser omentum 

 to the liver. If now he turns his fingers to the right he will 

 be able to pass them behind the portal vein and through the 

 epiploic foramen into the great sac. He should note, as he 

 passes his hand upwards, that the cavity of the omental bursa 

 is constricted, between the oesophagus above and to the left, 

 and the pylorus below and to the right, by two folds of peritoneum 

 which pass forwards from the posterior wall of the abdomen 



