In the human heart, the pulmonary trunk (pulmonary artery or main pulmonary artery) begins at the base of the right ventricle. It is short and wide ‐ approximately 5 cm (2 inches) in length and 3 cm (1.2 inches) in diameter. It then branches into two pulmonary arteries (left and right), which deliver de‐oxygenated blood to the corresponding lung. In contrast to the pulmonary arteries, the bronchial arteries supply mainly nutrition to the lungs themselves.

The right auricle pumps all the deoxygenated blood received in it from the body into the right ventricle, which in turn, pumps it into the lungs through the main pulmonary artery. The pulmonary artery, soon after its emergence, divides into two branches entering their respective lungs.

Inside the lungs, they divide and redivide several times to ultimately form capillaries around the air sacs. Veins arising from these capillaries join and rejoin to form two main pulmonary veins from each lung, which pour the oxygenated blood into the left auricle of the heart. Thus, the pulmonary artery carries deoxygenated blood from the heart to the lungs. It is one of the only arteries (other than the umbilical arteries in the fetus) that carry deoxygenated blood.