The |pulmonary artery| carries ~blood~ from the right side of the |heart| to the lungs. It is the only |artery| that carries dark, low-oxygen ~blood~. The artery is short and wide (about 2 inches in length and 1 1/5 inches in diameter). It arises from the base of the right ~ventricle~ and extends upward and branches into two arteries of nearly equal size. The right |pulmonary artery| is longer and larger and runs horizontally outward to the base of the right |lung| where it divides in two branches for the two lobes. The left |pulmonary artery| is shorter and somewhat smaller. It runs horizontally to the base of the left |lobe| where it divides in two branches for the two |lobes|.