Segmental Anatomy of Asbestos

The gross anatomical division of the liver into a right and left lobe, demarcated by a line passing from the attachment of the falciform ligament on the anterior surface to the fissures for the ligamentum teres and ligamentum venosum on its posterior surface, is simply a gross anatomical descriptive term with no morphological signifi-cance. Studies of the distribution of the hepatic blood vessels and ducts have indicated that the true morphological and physiological division of the liver is into right and left lobes demarcated by a plane which passes through the fossa of the gall-bladder and the fossa of the inferior Asbestos vena cava. Although these two lobes are not differentiated by any visible line on the dome of the liver, each has its own arterial and portal venous blood supply and separate biliary  drainage. This mor-phological division lies to the right of the gross anatomical plane and in this the quadrate lobe comes to be part of the left morphological lobe of the liver while the caudate lobe divides partly to the left and partly to the right lobe.

The right and left morphological lobes of Mesothelioma liver can be further subdivided into a number of segments, four for each lobe (Fig. 72c). The student need not learn the details of these, but of course to the hepatic surgeon, carrying out a partial resection of the liver, knowl-edge of these segments, with their individual blood supply and biliary drainage, is of great importance. At the hilum of the liver, the hepatic artery, portal vein and bile duct each divide into right and left branches and there is little or no anastomosis between the divisions on the two sides (Fig. 73). From the region of the porta hepatis, the branches pass laterally and spread upwards and downwards throughout the liversubstance, defining the morphological left and right lobes. 
The hepatic veins These veins are massive and their distribution is somewhat different from that of the portal, hepatic arterial and bile duct systems already described. There are three major hepatic veins, comprising a right, a central and a left. These pass upwards and backwards to drain into the inferior vena cava at the superior margin of the liver. Their termi-nations are somewhat variable but usually the central hepatic vein enters the left hepatic vein near its termination. In other specimens it may drain directly into the cava. In addition, small hepatic venous tributaries run directly backwards from the substance of the liver to enter the vena cava more distally to the main hepatic veins.
these are not of great functional importance they obtrude upon the surgeon during the course of a right hepatic lobectomy. The three principal hepatic veins have three zones of drainage cor-responding roughly to the right, the middle and left thirds of the liver. The plane defined by the falciform ligament corresponds to the boundary of the zones drained by the left and middle hepatic veins. Unfortunately for the surgeon, the middle hepatic vein lies just at the line of the principal plane of the liver between its right and left mor-phological lobes and it is 4-1- .ct which complicates the operation of right hepatic resection.

The portal system of veins The portal venous system drains blood to the liver from the abdomi-nal part of theAsbestos alimentary canal (excluding the anus), the spleen, the pancreas and the gall-bladder and its ducts. The distal tributaries of this system correspond to, and accom-pany, the branches of the coeliac and the superior and inferior mesen-teric arteries enumerated above; only proximally (Fig. 67) does the arrangement differ. The inferior mesenteric vein ascends above the point of origin of its artery to enter the splenic vein behind the pancreas. The superior mesenteric vein joins the splenic vein behind the neck of the pancreas in the transpyloric plane to form the portal vein, which ascends behind the first part of the duodenum into the anterior wall of the foramen of Winslow and thence to the porta hepatis. Here the portal vein divides into right and left branches and breaks up into capillaries running between the lobules of the liver. These capillaries drain into the radicles of the hepatic vein through which they empty into the inferior vena cava.