The caudate lobe is a (physiologically) independent part of the liver, supplied by the right and left hepatic artery and portal vein. Blood from the caudate lobe drains directly into the vena cava. It is also known as the lobule of Spiegel.
The caudate section of the liver is connected to the right lobe by a narrow bridge called the caudate process. This lies behind the porta hepatis, a deep crease in the liver. Below this is a small round appendage called the papillary process. This occasionally completely covers the inferior vena cava, bridging from the caudate lobe to the right liver lobe.
The caudate section of the liver is considered unique by physiologists because it has its own arterial supply and venous drainage. This is the reason it is seen as a separate lobe.
In the early stages of liver damage, the liver may become enlarged; however in the terminal (cirrhosis) stages the liver tends to shrink. The right lobe of the liver shrinks more than the caudate section. The normal, healthy ratio between the caudate and right lobe (when comparing mass) is less than 0.6.