484 THE PEEITONEUM. 



denum and a curve of the hepatic artery. From this opening the 

 lesser sac spreads out to the left behind the general or main sac 

 of the peritoneum. It covers a part of the posterior abdominal 

 wall, but in front and below it is applied to the back of the main 

 sac, to which it adheres except where the stomach is interposed. 

 Moreover, it indents, as it were, the back of the main sac, and 

 between the stomach and colon protrudes into it in form of a great 

 ])0uch — the bag of the omentum, — which thus has a double coat, 

 formed by the apposition of the membranes of both sacs. To trace this 

 arrangement more particularly : suppose a finger pushed into the 

 foramen of AVinslow, and tlie thumb brought to meet it from before, to 

 the left of the hepatic vessels; the membrane held between is double ; 

 its anterior layer (from the greater sac), turns round the hepatic 

 vessels into the foramen, and then belongs to the lesser sac. The 

 double membrane, so constituted, is the lesser or hepato-gastric omentum. 

 From the point indicated it may be followed to the transverse fissure of 

 the liver, where its laminte separate, the anterior, which has already 

 been traced from above, spreading on the adjacent part of the liver, 

 the posterior covering the lobulus Spigelii, where it will be again met 

 with. The attachment of the combined layers continues backwards 

 from the left end of the transverse fissure along the fossa ductus venosi 

 to the diaphragm, on which it runs a short way to reach the oesophagus,, 

 where the anterior lamina covers the end of that tube in front and on 

 the left, and the posterior lamina invests it on the right and behind. 

 From this point, as far as the pylorus, the lesser omentum is attached 

 to the lesser curvature of the stomach, where its laminae separate — one 

 covering the anterior and the other the posterior surface of the organ — 

 but meeting again at the great curvature, they pass down in conjunction 

 to a variable distance before the small intestine to form the anterior 

 part of the great omental sac, and then turn up to form its posterior 

 wall. Meeting next with the transverse colon, the two laminfe separate, 

 and enclose that intestine, but meet again behind it to form the trans- 

 verse mesocolon. This extends back to the lower border of the pancreas, 

 from which its inferior layer is continued down over the posterior wall 

 of the abdomen, and forms the mesentery, where it has been already 

 recognised. The superior layer, on the other hand, which, as will 

 be understood, belongs to the lesser sac, covers the front of the 

 pancreas, the cceliac artery and its main divisions with the adjacent 

 part of the diaphragm, and may extend to the left end of the pancreas 

 and lower end of the spleen, partially investing the latter organ and 

 forming part of the gastro-splenic ligament. It then goes forward 

 on the lobukis Spigelii to the transverse fissure, and the line of attach- 

 ment of the lesser omentum of which it then becomes the under 

 layer. More to the right the layer in question passes over the vena 

 cava, and continues into the general peritoneum beyond the foramen 

 of Winslow. The gastric and hepatic arteries, especially the former 

 (Huschke), may raise the membrane into folds which project into the 

 cavity. 



From the description given it will be understood that, as the 

 sides or walls of the great omental bag consist of two peritoneal 

 layers, its whole thickness (in its usually empty and collapsed 

 state) will comprehend four layers. But although the bag may be 

 inflated in its whole extent in the infantile body, its sides afterwards 



