"The proper hepatic artery bifurcates into the left and right hepatic arteries at or before reaching the porta hepatis. These are end arteries and supply the left and the right halves of the liver respectively. The left hepatic artery runs vertically towards the umbilical fissure and supplies segments 1, 2 and 3. It usually gives off a middle hepatic artery branch that runs towards the right side of the umbilical fissure and supplies segments 4a and 4b 2."