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 thrombus, or blood clot, forming which can dislodge and travel into the heart where it can travel to the lungs. This is a possible complication of immobility due to excessive bed rest following a surgery or disability, or an excessively sedentary lifestyle. 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