Couinaud classification (diagram)


The middle hepatic vein divides the liver into left and right lobes. The left hepatic vein divides the left lobe into medial (II,III) and lateral segments (IVa, IVb). The right hepatic vein divides the right hepatic lobe into anterior segments (V and VIII) and posterior segments (VI and VII). The caudate lobe (I) has a separate hepatic vein that drains directly into IVC, that is why in Budd-Chiari syndrome the caudate lobe becomes hypertrophic due to this separate drainage.