The foundation of modern liver surgery was laid by the pioneering independent anatomical works of Couinaud [1] and Healey [2, 3]. By using the corrosion casting method, both subdivided the liver into components, separated by watershed regions. While Couinaud used portal vein ramifications for subdividing, Healey used hepatic artery and bile ducts to define the liver anatomy. The branching pattern of the portal vein, hepatic artery, and bile duct is identical on the right side, resulting in identical categorization of second-order and third-order divisions. However, on the left side, the left portal vein divides into an umbilical branch (to segments 3 and 4) and a branch to segment 2, whereas the left hepatic artery and bile duct divide into medial (segment 4) and lateral branches (segments 2 and 3).