In Couinaud classification, segment IV of liver is:
The Couinaud classification divides the liver into 8 independent segments each of which has its own vascular inflow, outflow, and biliary drainage. Because of this division into self-contained units, each can be resected without damaging those remaining.
In Couinaud's classification
Segment I is............. Caudate lobe
Segment IV is............ Qudrate lobe
The caudate lobe is anatomically different from other lobes in that it often has direct connections to the IVC through hepatic veins, that are separate from the main hepatic veins.
The caudate lobe may be supplied by both right and left branches of the portal vein.
Caudate lobe
Quadrate lobe
Right lobe
Left lobe