lyTo 



HUMAN ANATOMY. 



backward in a curve to the right of the vena cava, keeping in the lower part of the 

 Hver and giving off successively a series of large branches to the front and right of 

 the organ. Smaller branches arise from the sides of these. The right primary 

 division soon gives off a large superior branch almost equal to itself, which describes 

 a similar but smaller curve at a higher level. The general course of the left subdi- 

 vision is towards the posterior angle of the organ, giving branches chiefly from its 

 anterior side, and also one that supplies the greater part of the quadrate lobe. The 

 lobe of Spigelius generally receives a chief branch near its lower end, which runs 

 upward within it. This branch is most often from the left subdivision, but it may 

 be from the right, or from the vessel directly behind the end of the portal vein. 

 There are several systems of so-called accessory portal veins around the liver in the 

 lesser omentum near the gall-bladder, about the diaphragm, and, most important, 

 in the falciform ligament, where the parianbilical veins communicate with veins of 

 the integument of the abdominal walls. These accessory vessels, small and incon- 

 spicuous under normal conditions, may become enlarged and important channels 



Fig. 1443- 



Portions of inferior and posterior surfaces of liver have been removed to show injected blood-vessels and bile- 

 ducts. Vena cava is somewhat displaced forward, its course being more vertical when supported on posterior sur- 

 face. Large upper branch of right division of portal vein is hidden by liver-substance. Portal vein and branches 

 are purple ; hepatic artery, red ; hepatic veins and vena cava, blue ; bile-ducts, yellow, uv, obliterated umbilical vein ; 

 vc, inferior vena cava. 



for the return of the blood conveyed by the portal vein when the hepatic circula- 

 tion is obstructed. Under such conditions the blood finds its way from the portal 

 vein into the accessory veins and by the anastomoses of the latter into the general 

 circulation. 



The hepatic veins carrying off the blood from the liver arise as the ?«/ra- 

 lobular veins, which empty into the S7iblobular, which join larger A'essels converging 

 towards the vena cava. At first the general direction of the small branches is paral- 

 lel to that of those of the portal system of the same size ; but the hepatic branches 

 always travel alone. The direction of the large branches as they near the vena cava 

 is at right angles to that of the portal. The arrangement of the hepatic branches is 

 in the main like that of the portal, but near the edge of the liver we find more 

 instances of the union of two rather small trunks meeting symmetrically like the 

 arms of a Y. The main trunks of the right lobe run between the upper and lower 

 branches of the portal. The upper end of the .vena cava is considerably enlarged, 

 and immediately below the diaphragm receives two large hepatic veins, a right and a 

 left one, from 15 to 20 mm. in diameter. The latter is formed by two large branches 

 that unite just before its end. Many small veins open into the vena cava at different 



