PORTAL 



635 



of the lesser omentum in company with tlie liepatic artery and the hepatic duct, it 

 enters the transverse or i)ortal Hssure of the Hver, and there divides into a right and 

 a left l)ranch. In this course it passes upwards and to the right, having hoth the 

 he{)atic artery and the common bile duct in front, the former to the left, the latter 

 to the right. It is surrounded by branches of the hepatic plexus of the sym- 

 l)athetic nerve, and by numerous lymphatic vessels and some glands. The con- 

 nective tissue sheath enclosing these structures is called the capsule of Glisson. 

 Just before it divides it is somewhat dilated, the dilated portion being called the 

 sinus of the portal vein. The division into right and left branches taki-s place 

 towards the riizlit end of the transverse fissure of the liver. The right branch is 

 shorter and thicker than the left, and supplies the right lobe of the liver and a 



Fig. 392. — The Veins of the Stomach and the Portal Veix. 

 (From a dissection by W. J. W;ilsham.) 



Cystic vfhi 



Right branch of 

 portal IV in 



Portal vein 



Hepatic artery 



Continuation of 



hepatic artery 



Gnstro-iiiiodennl 



branch of hepatic 



artery 



Pyloric win 



Right gastro- 

 epiploic vein 



Omental reins 



Left branch of 

 portal rein 



Left f/astro- 

 'jii/jloic rein 



branch to the quadrate lobe. The left branch is longer and smaller than the right, 

 and supplies the left lobe, and gives a Itranch to the Spigelian and (piadrate lolies. 

 It is joined, as it crosses the longitudinal fissure, by a fil)rous cord, known as the 

 round ligament of the liver or the oliliterated umbilical vein, and ]>osteriorly by a 

 second fibrous cord, the remains of the ductus venosus. In the feetus the blood 

 passes through the umbilical vein and ductus venosus directly into the vena cava, 

 a very small ([uantity only turning to the right and left into the brandies of the 

 portal vein. Before l)irth, the blood in that part of the left branch of the ])ortal 

 vein which lies between the trunk of the vena porta and the umbilical vein travels 

 from left to right; but after l)irth, as the portal circulation l)ecomes freely esta- 

 blislied and the umbilical vein and ductus venosus are obhterated, in the opposite 

 direction, i.e. from right to left. 



