434 DIGESTI^'E SYSTEM OF THE HORSE 



The pancreas is attached dorsally by connective tissue to the kidneys and 

 adrenal bodies, the gastro-phrenic ligament, the suspensory ligament of the spleen, 

 the posterior vena cava, the portal fissure, and the gastro-pancreatic fold. The 

 ventral surface is mainly attached by areolar tissue to the base of the caecum and 

 the terminal part of the great colon. 



There are almost invariably two ducts. The large one is termed the pan- 

 creatic duct (Ductus pancreaticus).' It is formed by the union of two radicles 

 which come from the right and left extremities, and passes through the duodenal 

 angle to end at the duodenal diverticulum alongside of the bile-duct. The duct 

 is nearly half an inch (ca. 1 cm.) wide, and is very thin walled. It is situated in the 

 substance of the gland near its dorsal surface; none of it is free. The accessory 

 pancreatic duct (Ductus pancreaticus accessorius)^ arises either from the chief 

 duct or its left radicle, and ends on a papilla in the duodenum opposite the chief 

 duct. 



Structure. — The pancreas belongs to the class of tubulo-alveolar glands, the 

 alveoli being long, like those of the duodenal glands; in other respects it resembles 

 the serous salivary glands very closely. It has no proper capsule and the lobules 

 are rather loosely united. 



Vessels and Nerves. — The arteries of the pancreas come from the branches of 

 the coeliac and anterior mesenteric arteries. The veins go to the portal vein. The 

 nerves are derived from the cceliac and mesenteric plexuses of the sympathetic. 



THE LIVER 



The liver (Hepar) is the largest gland in the body. It is situated obliquely 

 on the abdominal surface of the diaphragm. Its highest point is at the level of 

 the right kidney, its lowest on the left side, usually about three or four inches 

 (ca. 8 to 10 cm.) from the abdominal floor, opposite the ventral end of the seventh 

 or eighth rib. The greater part of it lies to the right of the median plane. 



It is red-bro'wTi in color and is rather friable. Its average weight is about ten 

 to twelve pounds (ca. 5 kg.), but in a large draft horse it weighs abouttwenty pounds. 

 When in the body, or if hardened in situ, it is stronglj^ curved and accurately adapted 

 to the abdominal surface of the diaphragm. When removed in the soft state, it 

 flattens out into a cake-like form quite different from its natural configuration. 

 It presents for description two surfaces, and a circumference which may be divided 

 into four borders. 



The parietal surface (Facies diaphragmatica) is strongly convex, and lies 

 against the diaphragm. It faces chiefly dorsally and for^vard. Its most anterior 

 part is opposite the ventral third of the sixth intercostal space or seventh rib. It 

 presents, just to the right of the median plane, a sagittal groove for the posterior 

 vena cava (Fossa venae cavae), which is partially embedded in the substance of the 

 gland. 



The visceral surface (Facies visceralis) faces in general ventrally and backward; 

 it is concave and irregular, being molded on the organs which lie against it. It 

 presents the follo-^ving features: (1) The portal fissure (Porta hepatis) is a depres- 

 sion above the middle of the surface and a little to the right of the median plane; " 

 through it the portal vein, hepatic artery, and hepatic plexus of nerves enter, and 

 the hepatic duct and lymph vessels leave the liver. The hepatic lymph glands are 

 also found here. The pancreas is attached at and to the right of the fissure, and 

 the lesser omentmn around it. Above the fissure is the caudate lobe (Lobus cau- 

 datus), which is continued to the right by the pointed caudate process (Processus 

 caudatus). (2) The gastric impression (Impressio gastrica) is an extensive con- 



1 Formerly termed the canal of Wirsung. 



^ Formerly called the ductus pancreaticus minor or duct of Santorini. 



