THE PERITONEUM. 



993 



As a result of closure of this foramen due to adhesive inflammation, a hydrops 

 saccatus can be formed by a collection of serum in the lesser sac, and the stomach 

 will rest on a sort of water-bed. 



Another rare anomaly is a hernia through this foramen. A great part of the 

 small intestines have worked their way through it by peristalsis into the lesser sac. 



The Lesser Sac or Bursa Omentalis. Between the mesogastrium and posterior 

 wall of the stomach there was originally a three-cornered space with its apex 

 turned to the left and base to the right (Figs. 599 and 600). During develop- 

 ment the base has been narrowed to the foramen of Winslow. The cavity is 

 called the lesser sac or omental bursa. Figure 606 shows that it sends a diver- 

 ticulum up behind the Spigelian lobe of the liver, another downward known as 

 the cavity of the great omentum, and in figure 610 we see the main chamber 

 behind the stomach sending off a third pouch to the spleen and left kidney. 



When the finger enters the foramen of Winslow it is able to mark out a cir- 

 cumscribed region confined by the Spigelian lobe anteriorly and the diaphragm 

 behind. Push the finger to the left until it is obstructed and let it descend ; at a 

 level below the papillary tubercle of the liver it will slip under a prominent band, 

 and can now ascend under the fundus of the stomach up to the posterior surface 

 of the resophagus ; we call then push over to the spleen, or, if the subject be 

 young enough, down into the great omentum. 



The lesser sac seems to be subdivided. Huschke called the first portion, 

 which receives the Spigelian lobe, the bursa omenti minoris, because it is just 

 behind the lesser omentum. 



The second large division going upward behind the stomach and downward 

 into the omentum and over to the spleen was the bursa omenti majoris. Each 



Papillary tubercle 



Cut edfje of peritoneum 



Descending 

 duodenum 



Spleen covered 

 'by peritoneum 



Cut edge of peritoneum 



FIG. 616. Bursa omentalis, opened from the front by an incision through the gastro-colic omentum A 

 probe passes through the foramen of Winslow and rests o'u the gastro-pancreatic ligament. (Henle.) 



communicates with the other by the foramen omenti majoris. These subdivisions 

 are still found, and the constricting band is still present, caused by the gastric 



63 



