THORAX AND ABDOMEN OF THE HORSE 103 



stomach and spleen with each other. A ligament, further, may have a 

 very close morphological resemblance to a mesentery, as is the case with 

 the broad ligament of the uterus. Some ligaments, the falciform of the 

 liver and one on each side of the urinary bladder, are peritoneal folds 

 with a free margin containing the remains of an embryonic blood vessel. 

 All peritoneal folds contain a varying amount of connective tissue and 

 fat, and many of them supply a means whereby vessels and nerves 

 reach the viscera. In some folds, notably in the mesenteiy of the 

 small intestine, lymph glands are readily discernible, and in some also — 

 in the broad ligament of the uterus, for example — there is an appreci- 

 able amount of unstriped muscular tissue. 



In connection with the peritoneum there are two omenta, a greater 

 and a lesser. The lesser omentunn (omentum minus) may be demon- 

 strated by turning the intestinal mass aside and then separating the 

 liver and stomach as far as possible. When this has been done, a loose 

 membranous sheet of peritoneum will be found stretching from the 

 liver to the lesser curvature of the stomach and the first part of the 

 duodenum. It is customary, for convenience of description, to divide 

 the lesser omentum into the hepato-duodenal and hepato-gastric 

 ligaments — names which sufficiently clearly indicate their connections. 



The greater omentum ^ (omentum majus) has a more complicated 

 series of connections. In the horse it is small and not disposed, as in 

 the dog, over the whole of the intestinal mass, but is generally invisible 

 when the abdomen is first opened. It has to be sought dorsal to the 

 larger intestine, immediately caudal to the stomach, where it is readily 

 recognised by its lace-like appearance. A variable amount of fat, 

 commensurate with the deposit of fat in the body in general, is 

 contained within the omentum. When the membrane is straightened 

 out it will be noticed that it apparently consists of two layers enclosing 

 a cavity. In reality, however, it is composed of four layers of peritoneum, 

 as will be demonstrated presently. In order to study the connections 

 of the omentum it is well to make an opening into the cavity (bursa 

 omentalis) enclosed within it. In general terms it may be stated that 

 the greater omentum is a loose double membrane with a ventral 

 attachment to the greater curvature of the stomach and a dorsal 

 attachment to the termination of the large colon and the commence- 

 ment of the small colon. It simplifies matters to regard the spleen as 

 insinuated between the layers of the ventral sheet of the omentum. 



The attachments of the greater omentum should be followed, 

 beginning at the greater curvature of the stomach. An examination of 

 the gastric line of attachment at once convinces the dissector that what 



' Omentum [L.], the fat-containing membrane that covers the intestines. 



