THORAX AND ABDOMEN OF THE HORSE 117 



(plica gastropancreatica) connects the saccus ciecus to the pancreas and 

 the duodenum. 



The dissector shoukl leave the examination of the interior of the 

 stomach until later. 



The Duodenum (Duodenum). — The duodenum, about one metre in 

 length, is the most distinctive part of the small intestine, inasmuch as 

 its position is definitely fixed. Beginning at the pylorus, the first part 

 of the tube is sigmoid and lies on the right lateral lobe of the liver, 

 ending, after a short course to the right, at the first flexure (flexura 

 prima) which turns towards the pelvis. The second part (pars 

 descendens) runs ventral to the liver and the right kidney, and ends at 

 the second flexure (flexura secunda), which, turning to the left, carries 

 the duodenum across the median plane, behind the root of the mesentery 

 and opposite the third or fourth lumbar vertebra, to end in the 

 jejunum. 



The calibre of the duodenum is not uniform, for, as it leaves the 

 pylorus, there is a reniform dilatation, with a convexity looking in a 

 dorsal direction. 



The first part of the duodenum is connected with the liver by a 

 narrow hepato-duodenal ligament (ligamentum hepatoduodenale), and 

 the second part is attached to the right kidney by the i^eno-duodenal 

 ligament (ligamentum renoduodenale). The peritoneum also forms a 

 short mesentery that passes to the saccus dorsalis of the c?ecum and the 

 right dorsal colon. 



The pancreas. — The pancreas ^ is a lobulated gland of pinkish- 

 yellow or grey colour when fresh, but after death it quickly assumes a 

 dark grey or even greenish tint. In shape it is irregularly triangular, 

 with its base directed towards the right ; its weight is about 350 grammes 

 in a horse of average size. In general appearance the pancreas resembles 

 the salivary glands, but its lobules are more readily separated because of 

 the looseness of the interlobular connective tissue. The gland lies near 

 the vertebral column (opposite the sixteenth, seventeenth and eighteenth 

 thoracic vertebrae), ventral to the aorta and caudal vena cava. Its cranial 

 border touches the coeliac artery, while its caudal border is in contact 

 with the cranial mesenteric artery, and is notched by the root of the 

 mesentery. 



The greater bulk of the gland lies to the right of the median plane, 

 where it forms a head (caput pancreatis) related to the duodenum and 

 the right lateral lobe of the liver. The much smaller cauda pancreatis 

 is to the left, and in contact with the saccus cfecus of the stomach, the 



^ Tras (pas (pan) ) [Gr.], all ; /cpeas (creas) [Gr.], flesh. 



