[2] In the centre of each segment there is a branch of the portal vein, hepatic artery and bile duct.

[1] The caudate lobe is a separate structure which receives blood flow from both the right- and left-sided vascular branches.

The Spiegel lobe has its portal venous and biliary branches ramified mainly from the left-side tract.

The Paracaval portion has the portal venous branches ramified mainly from the left portal vein, while the biliary branches of this portion drained into the right and left biliary tracts at almost equal frequencies.

Segment IV lies lateral to the falciform ligament and is subdivided into IVa (superior) and IVb (inferior).