left pulmonary artery, the shorter and smaller of two arteries conveying venous blood from the heart to the lungs, rising from the pulmonary trunk, connecting to the left lung, and tending to have more separate branches than the right pulmonary artery. In the fetus, it is larger and more important than the right pulmonary artery because it provides the ductus arteriosus that degenerates to become a ligament after birth. Compare right pulmonary artery.
