Hepatic segmentation

The hepatic segmentation (lobes, parts, divisions and segments) is the organisation of the liver into lobes (classic classification) or in parts, divisions and segments, based on the portal blood supply (distribution for the hepatic portal veins, arteries and ducts). There are different methods to name and describe the functional hepatic segmentation, but the mainly used is the Couinaud classification that is relevant for surgical anatomy.

The lobes of the liver are classically four:

• a smaller left lobe 

• a larger right lobe separated along the attachment of the falciform ligament, that contains:

  • the caudate lobe

  • the quadrate lobe

The hepatic segmentation with parts, divisions and segments (Couinaud classification) describes the functional liver anatomy (preferred over morphological liver anatomy).

• Left part of liver

  • Left lateral division, sudivided by the portal plane into:

    • Segment II: Left posterior lateral segment

    • Segment III: Left anterior lateral segment

  • Left medial division

    • Segment IV: left medial segment; may be subdivided in two subsegments by the portal plane(Bismuth):

      • IVa: Superior subsegment of the medial segment

      • IVb: Inferior subsegment of the medial segment

• Posterior part of liver

  • Segment I: Caudate lobe - Posterior segment of liver

• Right part of liver

  • Right medial division, sudivided by the portal plane into:

    • Segment V: Anterior medial segment of liver

    • Segment VIII: Posterior medial segment of liver

  • Right lateral division, sudivided by the portal plane into:

    • Segment VI: Anterior lateral segment of liver

    • Segment VII: Posterior lateral segment of liver