Anatomy of left atrium - Intro

Left atrium is the left upper chamber of the heart which receives oxygenated blood from the lungs through the four pulmonary veins. They are the right superior, right inferior, left superior and left inferior pulmonary veins. Pulmonary veins join the posterior part of the left atrium which is smooth and formed by the incorporation of the embryonic single pulmonary vein and its branches into the left atrium.