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858 THE VASCULAR SYSTEM. 
omentum; continuing its upward course, it hes behind the common bile-duet and 
hepatic artery, and in front of the foramen of Winslow; it ultimately reaches the 
right end of the transverse fissure of the liver, where it ends by dividing into a 
short and wide right and a longer and narrower left branch. Just before its 
termination it enlarges, forming the sinus of the portal vein. 
The right branch generally receives the cystic vein and then enters the right lobe 
of the liver, in which it breaks up into numerous branches which terminate in the 
portal capillaries round the periphery and in the substance of the liver lobules. 
The left branch runs from right to left along the transverse fissure, giving off 
branches to the Spigelian and quadrate lobes; it crosses the longitudinal fissure, 
and ends in a similar manner to the right branch, but in the substance of the left 
lobe of the liver. 
As it crosses the longitudinal fissure, the left branch of the portal vein is joimed 
in front by the round ligament of the liver, a fibrous cord which is the remains of the 
left umbilical vein of the fcetus; and, somewhat to the right of the attachment of 
the round ligament anteriorly, a fibrous cord springs from it posteriorly and 
connects it with the upper part of the inferior vena cava; this cord is the remains 
of the ductus venosus, a blood-vessel of the fcetus, through which blood coming 
from the placenta, by the umbilical vein, passed into the inferior vena cava 
without going through the liver. 
The portal vein is accompanied by numerous lymphatic vessels, and it is 
surrounded in the gastro-hepatic omentum by filaments of the hepatic plexus 
of nerves. 
Tributaries.—Soon after its formation the portal vein receives the coronary and 
pyloric veins, and the cystic vein opens into its right branch. 
The coronary vein (v. coronaria ventriculi) commences in the gastro-hepatic omentum 
by the union of tributaries from both surfaces of the stomach. It runs to the left 
between the layers of the gastro-hepatic omentum, and along the lesser curvature of the 
stomach, with the corresponding artery, to the wsophagus, where it receives cesophageal 
tributaries. It then turns backwards in the left pancreatico-gastric fold, and reaches the 
posterior wall of the abdomen, where it again changes its direction to run from left to 
right, behind the lesser sac of the peritoneum, to the right pancreatico-gastric fold, at the 
root of which it opens into the portal vein, 
The pyloric vein (v. pylorica) is a small vessel which is formed by the union of 
tributaries from the upper parts of both surfaces of the stomach. It runs from left to 
right along the right portion of the lesser curvature, between the layers of the gastro- 
hepatic omentum, and terminates in the portal vein, after that vessel has entered the 
gastro-hepatic omentum. 
The cystic vein (v. cystica) is formed by the union of tributaries which accompany 
the branches of the cystic artery on the upper and lower surfaces of the gall-bladder ; it 
ascends along the cystic duct, and as a rule terminates in the right branch of the portal 
vein. 
THE MESENTERIC AND SPLENIC VEINS. 
The superior mesenteric vein (v. mesenterica superior) commences in the right iliac 
fossa in connection with the lower part of the ileum. It ascends along the right side of 
the superior mesenteric artery in the root of the mesentery, forming a curve with the 
convexity to the left. 
As it ascends it passes in front of the right ureter, the lower part of the inferior vena 
cava, the third part of the duodenum, and the lower part of the head of the pancreas ; 
and, after passing behind the root of the transverse mesocolon, it terminates behind 
the neck of the pancreas by uniting with the splenic vein to form the portal vein. 
Its tributaries correspond with the branches of the superior mesenteric artery. It is formed 
by the union of the ileo-ceecal and appendicular veins. In front and towards the left side the 
tributaries (vv. intestinales) from between the folds of the mesentery enter it; the right colic 
and ileo-colic veins enter its right side; the middle colic vein joins it in front at the lower border 
of the head of the pancreas, and close to its termination it receives the right gastro-epiploic 
and the pancreatico-duodenal veins. 
The right gastro-epiploic vein (v. gastroe-piploica dextra) runs from left to right along the 
lower border of the stomach, and between the two anterior layers of the great omentum. It 
receives tributaries from both surfaces of the stomach, and near the pylorus turns backwards in 
