Pulmonary vein three and five in the healthy population. The two left lobar veins may be united as a single pulmonary vein in about 25% of people; the two right veins may be united in about 3%. The pulmonary veins play an essential role in respiration, by receiving blood that has been oxygenated in the alveoli and returning it to the left atrium. As part of the pulmonary circulation they carry oxygenated blood back to the heart, as opposed to the veins of the systemic circulation which carry deoxygenated blood. A rare genetic defect of the pulmonary veins can cause them to
Deep vein of the thigh Deep vein of the thigh The deep vein of the thigh, (profunda femoris vein or deep femoral vein) is a large deep vein in the thigh. It receives blood from the inner thigh and proceeds superiorly and medially running alongside the profunda femoris artery to join with the femoral vein approximately at the level of the inferior-most portion of the ischial tuberosity. The deep vein of the thigh contributes the largest volume of blood to the femoral vein. The deep vein of the thigh is commonly affected by phlebitis which can be a dangerous condition in the case of a