Vein: Pulmonary vein
Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow.
Diagram of the alveoli with both cross-section and external view.
Latin	venae pulmonales
Gray's	subject #165 642
Drains from	lungs
Drains to	left atrium
Artery	pulmonary artery
Precursor	truncus arteriosus
MeSH	Pulmonary+Veins

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A pulmonary vein is a large blood vessel of the human circulatory system that carries blood from the lungs to the left atrium of the heart. There are four pulmonary veins, two from each lung. They carry oxygenated blood, which is unusual since almost all other veins carry deoxygenated blood.

[edit] Types

They are four in number, two from each lung, and are destitute of valves. They are

• right inferior
• right superior
• left inferior
• left superior

[edit] Path

They commence in a capillary net-work upon the walls of the air sacs, where they are continuous with the capillary ramifications of the pulmonary artery, and, joining together, form one vessel for each lobule.

These vessels uniting successively, form a single trunk for each lobe, three for the right, and two for the left lung.

The vein from the middle lobe of the right lung generally unites that from the upper lobe, so that ultimately two trunks from each lung are formed; they perforate the fibrous layer of the pericardium and open separately into the upper and back part of the left atrium.

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.

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.

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

[edit] Additional images

Bronchial anatomy	Bronchi, bronchial tree, and lungs	Pulmonary circuit	Alveolus diagram
Heart seen from above.	Transverse section of thorax, showing relations of pulmonary artery.	Pulmonary vessels, seen in a dorsal view of the heart and lungs.	Base and diaphragmatic surface of heart.
The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind.	Left atrium

[edit] External links

• SUNY Figs 19:05-08
• Illustration at infomat.net

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.