Pulmonary vv.

The pulmonary veins are large blood vessels that receive oxygenated blood from the lungs and drain into the left atrium of the heart. There are four pulmonary veins, two from each lung. The pulmonary veins are among the few veins that carry oxygenated blood.

Two pulmonary veins emerge from each lung hilum. An inferior and superior pulmonary vein drains each lung, so there are four pulmonary veins in total. The pulmonary veins are fixed to the pericardium and travel alongside the pulmonary arteries. 

At the root of the lung, the superior pulmonary vein lies in front of and a little below the pulmonary artery. The inferior pulmonary vein is situated at the lowest part of the lung hilum. Posterior to the pulmonary veins are the main bronchi. 

The right superior and inferior pulmonary veins pass behind the right atrium and superior vena cava. The left superior and inferior pulmonary veins pass in front of the descending thoracic aorta.