8o4 



A MANUAL OF ANATOMY 



The average diameter of a hepatic lobule is v,^^ inch. One of its 

 surfaces is called the base. It is by this surface that the lobule is 

 set upon the wall of a sublobulai vein, and the intralobular or central 

 vein, having emerged from the lobule through the centre of its base, 

 opens at once into the sublobular vein. The lobules, therefore, 

 relatively to the sublobular veins, on which they are ranged, are 

 sessile. When a sublobular vein is opened and viewed from within, 

 an appearance something like mosaic work presents itself, the 

 closely-set bases of the lobules being visible through the thin wall 

 of the vein, and the minute openings of the intralobular or central 

 veins appearing in the centre of each base. Each lobule is com- 

 posed of hepatic cells, permeated by capillary networks of blood- 

 vessels and bile capillaries. 



Bloodvessels. — The liver derives its blood from two sources, 

 namely, the vena portae, and the hepatic 

 artery. These two vessels, together with 

 the hepatic duct, are invested by the capsule 

 of Glisson at the portal fissure. Their several 

 branches, ensheathed by prolongations of 

 Glisson's capsule, ramify from this point 

 throughout the liver, being contained in 

 the system of canals, known as portal canals. 

 Each of these canals contains (i) a branch 

 of the vena portae, (2) a branch of the hepatic 

 artery, accompanied by a plexus of nerves, 

 (3) lymphatic vessels, and (4) a minute duct, 

 all these being loosely surrounded by a pro- 

 longation of Glisson's capsule. 



The vena portae ramifies within the liver 

 like an artery. In the portal canals its 

 branches receive as tributaries small cap- 

 sular and vaginal veins, and they go on 

 ramifying until they arrive at the inter- 

 lobular areas. Here they anastomose freely with one another 

 around the lobules, and so form the interlobular plexuses. The 

 branches which arise from these plexuses enter the lobules on all 

 sides except their bases, and form in the interior of each lobule 

 an intralobular plexus. From this plexus a few radicles converge 

 towards the centre of the lobule, where they form by their union 

 the intralobular or central vein. The portal blood, though dark 

 in colour, is very rich, being derived from, amongst other sources, 

 the stomach and small intestine. 



The hepatic artery is a branch of the coeliac axis. As its 

 branches traverse the portal canals they give off capsular branches 

 to the fibrous capsule of the liver, and vaginal branches, which supply 

 the walls of the vessels in the portal canals, as well as their Glis- 

 sonian sheaths. The branches of the artery finally end as minute 

 interlobular arteries, which supply the walls of the interlobular 



Fig. 345. — Section of 

 THE Liver, showing 

 A Large Hepatic 

 Vein and its Tribu- 

 taries (after Kier- 

 nan). 



