578 VESSELS AND NERVES OF THE LIVER. 



Vessels and Nerves. The vessels entering into the structure of the 

 liver are also five in number; they are the 



Hepatic artery, 

 Portal vein, 

 Hepatic veins, 

 Hepatic ducts, 

 Lymphatics. 



The Hepatic artery, portal vein, and hepatic duct enter the liver at 

 the transverse fissure, and ramify through portal canals to every part of 

 the organ ; so that their general direction is from below upwards, and 

 from the centre towards the circumference. 



The Hepatic veins commence at the circumference, and proceed from 

 before backwards, to open into the vena cava, on the posterior border 

 of the liver. Hence the branches of the two veins cross each other 

 in their course. 



The portal vein, hepatic artery, and hepatic duct are moreover enve- 

 loped in a loose areolar tissue, the capsule of Glisson, which permits them 

 to contract upon themselves when emptied of their contents; the hepatic 

 veins, on the contrary, are closely adherent by their parietes to the 

 surface of the canals in which they run, and are unable to contract. 

 By these characters the anatomist is enabled, in any section of the liver, 

 to distinguish at once the most minute branch of the portal vein from 

 the hepatic vein : the former will be found more or less collapsed, and 

 always accompanied by an artery and duct, and the latter widely open 

 and solitary. 



The Lymphatics are described in the Chapter dedicated to those 

 vessels. 



The Nerves of the liver are derived from the systems both of animal 

 and organic life ; the former proceed from the right phrenic and pneu- 

 mogastric nerves, and the latter from the hepatic plexus. 



Structure and Minute Anatomy of the Liver. 



The Liver is composed of lobules, of a connecting medium, called 

 Glisson's capsule, of the ramifications of the portal vein, hepatic duct, 

 fiepatic artery, hepatic veins, lymphatics, and nerves, and is enclosed and 

 retained in its proper situation by the peritoneum. 



The Lobules are small granular bodies, of about the size of a 

 millet seed, of an irregular form, and presenting a number of rounded 

 projecting processes upon their surface. When divided longitudinally, 

 they have a foliated appearance, and transversely, a polygonal outline, 

 with sharp or rounded angles, according to the smaller or greater 

 quantity of Glisson's capsule contained in the liver. Each lobule is 

 divided upon its exterior into a base and a capsular surface* The 

 base corresponds with one extremity of the lobule, is flattened, and 



