The hepatic artery proper splits off the common hepatic artery. For part of its course, it runs near the portal vein and the common bile duct. As a result, it forms part of the structure know as the portal triad, which also includes lymphatic vessels and a branch of the vagus nerve. In this respect, the word 'triad' is misleading, as the structure contains more than three elements. Historically, the distinction changed over the years as anatomical components were added.
Branching of the hepatic artery proper varies from person to person. Classically, it splits into left and right branches, called the left and right hepatic arteries. The right branch crosses in front of the portal vein and travels to the left of the bile duct. The left branch moves upward along the left side of the common hepatic duct. These arteries both supply the liver with oxygenated blood.
The hepatic artery proper should not be confused with the hepatic veins, which are blood vessels that remove oxygen-depleted blood from the liver.