THE ABDOMEN. 225 



the duodenum. It is supplied with blood from the coeliac 

 and anterior mesenteric arteries ; its blood passes into vena 

 portse. 



The liver is another important accessory gland of diges- 

 tion. It is that chocolate coloured body found in the 

 anterior part of the abdomen inclined to the right side 

 lying in contact with the diaphragm anteriorly, while 

 the duodenum courses from below upwards over its posterior 

 surface. It is thickest in the centre, and grows gradually 

 thinner towards its outer circumferent margin. It is 

 divided by deep fissures into lobes, of which there are 

 three principal and several accessory. The right lobe is 

 the largest, and is connected to the left by the middle. Its 

 anterior surface is smooth, invested by peritoneum ; its 

 superior margin presents a depression, fossa renalis, on 

 which the right kidney rests; from this part the right 

 lateral ligament runs, and superficially through the supero- 

 anterior part of the right lobe, the posterior vena cava 

 passes from the right side of the spine to foramen dex- 

 trum. The posteror surface of the right lobe presents 

 superiorly a peculiar triangular accessory lobe, the lohus 

 Spigelii vel caudatus. The external and inferior margins 

 are free while the inner is in connection with the middle 

 lobe, which anteriorly receives the falciform and round 

 ligaments. Posteriorly, it presents the porta or transverse 

 fissure, which extends to the right and left lobes, and to which 

 the arteries resulting from division of the hepatic branch of 

 the coeliac axis pass, and also the vena portse and gastro- 

 hepatic omentum, between the folds of which the nerves 

 and lymphatics run, and also the hepatic duct, which meets 

 the pancreatic duct, and the vessel thus formed opens into 

 the duodenum. (There is no gall-bladder in the horse, 

 hence no cystic duct, as in other animals.) The inferior 

 margin of the middle lobe is divided by numerous iissures 

 into several almost equal parts, between two of which the 

 round ligament passes in terminating. This is the lohus 

 scissatus. The left margin of the middle lobe blends with 

 the right of the left lobe, to the superior margin of which 

 the left lateral ligament is attached. Its other margins are 

 regular, and its surfaces smooth. On carefully examining 

 the surface of the liver we may see that it is _ mapped out 

 into minute polygonal divisions or lohuli, which are found 

 to be shaped like an ivy leaf and consists of a number of 



