434 DIGESTIVE 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 em.) 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 bemg 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 coeliac 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 em.) from the abdominal floor, opposite the ventral end of the seventh 
or eighth rib. The greater part of it hes to the right of the median plane. 
It is red-brown 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 about twenty pounds. 
When in the body, or if hardened in situ, it is strongly 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 forward. 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 vene cave), 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 following 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 omentum 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. 
2 Formerly called the ductus pancreaticus minor or duct of Santorini. 
