Path
The pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart. In humans there are normally four pulmonary veins, two from each lung. 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.
Occasionally the three veins on the right side remain separate, and not infrequently the two left pulmonary veins end by a common opening into the left atrium. Therefore, the number of pulmonary veins opening into the left atrium can vary between three and five in the healthy population.
The right pulmonary veins pass behind the right atrium and superior vena cava; the left in front of the descending thoracic aorta. At the root of the lung, the superior pulmonary vein lies in front of and a little below the pulmonary artery; the inferior is situated at the lowest part of the hilus of the lung and on a plane posterior to the upper vein. Behind the pulmonary artery is the bronchus. Within the pericardium, their anterior surfaces are invested by the serous layer of this membrane.
Read more about this topic: Pulmonary Vein
Famous quotes containing the word path:
“The purifying, healing influence of literature, the dissipating of passions by knowledge and the written word, literature as the path to understanding, forgiveness and love, the redeeming might of the word, the literary spirit as the noblest manifestation of the spirit of man, the writer as perfected type, as saint.”
—Thomas Mann (1875–1955)
“We are the pioneers of the world; the advance-guard, sent on through the wilderness of untried things, to break a new path in the New World that is ours.”
—Herman Melville (1819–1891)
“... my aim is now, as it has been for the past ten years, to make myself a true woman, one worthy of the name, and one who will unshrinkingly follow the path which God marks out, one whose aim is to do all of the good she can in the world and not be one of the delicate little dolls or the silly fools who make up the bulk of American women, slaves to society and fashion.”
—Ellen Henrietta Swallow Richards (1842–1911)