STRUCTURAL ANATOMY OF THE LIVER. 523 



ramify in the proper capsule, on the convex and concave surface of the 

 liver, and in the ligaments. These are the capsular arteries." Where 

 the capsule is well developed, " these vessels cover the surfaces of the 

 liver with a beautiful plexus," and " anastomose with branches of the 

 phrenic, internal mammary, and supra-renal arteries," and with the epi- 

 gastric. 



The Lobular branches, extremely minute and few in number, are the 

 nutrient vessels of the lobules, and terminate in the lobular venous plexus. 



All the venous blood resulting from the distribution of the hepatic 

 artery, even that from the vasa vasorum of the hepatic veins, is returned 

 into the portal vein. 



The Hepatic veins commence in the substance of each lobule by minute 

 venules, which receive the blood from the lobular venous plexus, and 

 converge to form the intralobular vein. The intralobular vein passes 

 through the central axis of the lobule, and through the middle of its base, 

 to terminate in a sublobular vein ; and the union of the sublobular veins 

 constitutes the hepatic trunks, which open into the inferior vena cava. 

 The hepatic venous system consists, therefore, of three sets of vessels ; 

 intralobular veins, sublobular veins, and hepatic trunks. 



The Sublobular veins are contained in canals formed solely by the bases 

 of the lobules, with which, from the absence of Glisson's capsule, they are 

 in immediate contact. Their coats are thin and transparent ; and, if they 

 be laid open by a longitudinal incision, the bases of the lobules will be 

 distinctly seen, separated by interlobular fissures, and perforated through 

 the centre by the opening of the intralobular vein. 



The Hepatic trunks are formed by the union of the sublobular veins ; 

 they are contained in canals (hepatic-venous) similar in structure to the 

 portal canals, and lined by a prolongation of the proper capsule. They 

 proceed from before backwards, and terminate, by two large openings 

 (corresponding to the right and left lobe of the liver) and several smaller 

 apertures, in the inferior vena cava. 



Summary. The liver has been shown to be composed of lobules ; the 

 lobules (excepting at their bases) are invested and connected together, 

 the vessels supported, and the w r hole organ enclosed, by Glisson's capsule, 

 and they are so arranged, that the base of every lobule in the liver is in 

 contact with an hepatic vein (sublobular). 



The Portal vein distributes its numberless branches through portal 

 canals, which are channeled through every part of the organ ; it brings the 

 returning blood from the chylopoietic viscera ; it collects also the venous 

 blood from the ultimate ramifications of the hepatic artery in the liver 

 itself. It gives ofF branches in the canals, which are called vaginal, and 

 form a venous vaginal plexus ; these give off interlobular branches, and 

 the latter enter the lobules and form lobular venous plexuses, from the 

 blood circulating in which the bile is secreted. 



The Bile in the lobule is received by a network of minute ducts, the 

 lobular biliary plexus ; it is conveyed from the lobule into the interlobular 

 ducts ; it is thence poured into the biliary vaginal plexus of the portal 

 canals, and thence into the excreting ducts, by which it is carried to the 

 duodenum and gall-bladder, after being mingled in its course with the 

 mucous secretion from the numberless muciparous follicles in the walls of 

 the ducts. 



The Hepatic artery distributes branches through every oortal cana, ; 



