Segmental anatomy

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 significance. 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 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 morphological 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 (Fig. 72).

Inferior vena cava Morphological left lobe

Inferior vena cava Morphological left lobe

Liver Dome Anatomy
Morphological right lobe
Segmental Fissures Caudate Lobe

Fig. 72 The morphological right and left lobes of the Liver shown separated by the dotted line: (a) anterior and (b) ventral aspect. Note that the quadrate lobe is morphologically a part of the left lobe while the caudate lobe belongs to both right and left lobes. (c) The further segmental divisions of the liver.

Fig. 72 The morphological right and left lobes of the Liver shown separated by the dotted line: (a) anterior and (b) ventral aspect. Note that the quadrate lobe is morphologically a part of the left lobe while the caudate lobe belongs to both right and left lobes. (c) The further segmental divisions of the liver.

The right and left morphological lobes of the 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, knowledge 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 down-

Fig. 73 (a) Distribution of hepatic arteries. (b) Distribution of hepatic biliary ducts. Note that the quadrate lobe is supplied exclusively by the left hepatic artery and drained by the left hepatic duct. The caudate lobe is supplied by each.

Fig. 73 (a) Distribution of hepatic arteries. (b) Distribution of hepatic biliary ducts. Note that the quadrate lobe is supplied exclusively by the left hepatic artery and drained by the left hepatic duct. The caudate lobe is supplied by each.

Left Hepatic Artery Branches

wards throughout the liver substance, defining the morphological left and right lobes.

The hepatic veins (Figs 72c, 74)

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 terminations 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. Although these are not of great functional importance they obtrude upon the surgeon during the course of a right hepatic lobectomy.

Hepatic veins

Right Centra! Left

Common hepatic duct

Right Centra! Left

Common hepatic duct

Falciform Ligament Anatomy

_ Falciform ligament

Accessory hepatic vein

Fig. 74 Liver split open to demonstrate the tributaries of the hepatic vein.

_ Falciform ligament

Accessory hepatic vein

Fig. 74 Liver split open to demonstrate the tributaries of the hepatic vein.

The three principal hepatic veins have three zones of drainage corresponding 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 morphological lobes and it is this fact which complicates the operation of right hepatic resection (Fig. 74).

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Responses

  • clara
    Where is rt inferior liver lobe?
    8 years ago
  • ky
    What segment is the dome of the liver?
    8 years ago

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