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Pulmonary artery

The pulmonary arteries carry blood from the right ventricle to the lungs. A single pulmonary trunk leaves the ventricle and divides into the left and right pulmonary arteries. (OpenStax A&P 2e, 20.5 and 19.1; StatPearls, Thorax, Heart Pulmonary Arteries and Heart Pulmonic Valve)

Latin arteria pulmonalis (Wikipedia, Pulmonary artery, CC BY-SA 4.0) · FMA66326 · Cardiovascular system

The great vessels from the front, all faded except the pulmonary artery, highlighted from its trunk beside the ascending aorta out into its branches in both lungs.
The pulmonary artery in place, seen from the front. Render: ScienceQuest, CC BY 4.0. Meshes: BodyParts3D, © The Database Center for Life Science, CC BY 4.0
The pulmonary artery on its own, seen from above, its trunk dividing into right and left branches that spread through both lungs.
The pulmonary artery alone, seen from above. Render: ScienceQuest, CC BY 4.0. Meshes: BodyParts3D, © The Database Center for Life Science, CC BY 4.0

Open it in the Great Vessels Explorer See it alone in 3D

Where is the pulmonary artery?

The main pulmonary artery and its two branches sit in the middle mediastinum. The main vessel runs along the left side of the ascending aorta as the great vessels leave the heart. (StatPearls, Thorax, Heart Pulmonary Arteries)

It is short and wide, about 5 cm long and 2 to 3 cm across. It divides at about a right angle at the level of the carina, T4, just below the aortic arch. (StatPearls, Thorax, Heart Pulmonary Arteries)

What does the pulmonary artery carry?

The pulmonary trunk and its branches carry deoxygenated blood, which the lungs then load with oxygen. (OpenStax A&P 2e, 19.1; StatPearls, Thorax, Heart Pulmonary Arteries)

Within each lung the artery divides into lobar, segmental and smaller branches, which end as the capillary network around the alveoli, where the blood picks up oxygen. (OpenStax A&P 2e, 22.2; StatPearls, Thorax, Heart Pulmonary Arteries)

The pulmonary semilunar valve at the base of the trunk opens in systole and closes in ventricular diastole, keeping blood from flowing back into the right ventricle. (OpenStax A&P 2e, 20.5; StatPearls, Heart Pulmonic Valve)

How do the right and left pulmonary arteries reach the lungs?

The right pulmonary artery passes behind the ascending aorta and in front of the descending aorta. It lies in front of the right main bronchus. The left passes in front of the descending aorta, above the left main bronchus. (StatPearls, Thorax, Heart Pulmonary Arteries)

The mnemonic RALS sums this up: right anterior, left superior, each artery against its own main bronchus. (StatPearls, Thorax, Heart Pulmonary Arteries)

What linked the pulmonary trunk to the aorta before birth?

Before birth, the ductus arteriosus joins the pulmonary trunk to the aorta. After birth it closes and leaves the ligamentum arteriosum. (OpenStax A&P 2e, 20.6; StatPearls, Thorax, Heart Pulmonary Arteries and Thorax, Heart Ductus Arteriosus)

Which pulmonary artery variants are known?

In a pulmonary sling, the left pulmonary artery arises from the back of the right one and runs between the esophagus and the trachea. (StatPearls, Thorax, Heart Pulmonary Arteries)

Where the sources differ

The names differ. OpenStax asks you to call the vessel leaving the heart the pulmonary trunk and keep pulmonary artery for its two branches. StatPearls calls that first vessel the main pulmonary artery. (OpenStax A&P 2e, 20.5; StatPearls, Thorax, Heart Pulmonary Arteries)

The pulmonary artery at a glance
Feature Detail and source
Arises from Right ventricle, as the pulmonary trunk (OpenStax A&P 2e, 20.5; StatPearls, Heart Pulmonic Valve and Thorax, Heart Pulmonary Arteries)
Main vessel About 5 cm long, 2 to 3 cm across (StatPearls, Thorax, Heart Pulmonary Arteries)
Divides at The carina, T4, below the aortic arch (StatPearls, Thorax, Heart Pulmonary Arteries)
Carries Deoxygenated blood to the lungs (OpenStax A&P 2e, 19.1; StatPearls, Thorax, Heart Pulmonary Arteries)

Touches in this model

Measured on the BodyParts3D meshes: surfaces within 2 mm of the pulmonary artery, nearest first, 12 of 24.

Sources

  1. OpenStax Anatomy and Physiology 2e, section 20.5, Circulatory Pathways. CC BY-NC-SA 4.0. Read 2026-10-25.
  2. OpenStax Anatomy and Physiology 2e, section 19.1, Heart Anatomy. CC BY-NC-SA 4.0. Read 2026-10-25.
  3. StatPearls, Anatomy, Thorax, Heart Pulmonary Arteries. William D. Tucker; Carly Weber; Bracken Burns. Last update July 24, 2023. CC BY-NC-ND 4.0. Read 2026-10-25.
  4. StatPearls, Anatomy, Thorax, Heart Pulmonic Valve. Joshua Henrina Sundjaja; Bruno Bordoni. Last update July 24, 2023. CC BY-NC-ND 4.0. Read 2026-10-25.
  5. OpenStax Anatomy and Physiology 2e, section 22.2, The Lungs. CC BY-NC-SA 4.0. Read 2026-10-25.
  6. OpenStax Anatomy and Physiology 2e, section 20.6, Development of Blood Vessels and Fetal Circulation. CC BY-NC-SA 4.0. Read 2026-10-25.
  7. StatPearls, Anatomy, Thorax, Heart Ductus Arteriosus. Trevor Huff; Raheel Chaudhry; Yingyot Arora; Kunal Mahajan. Last update July 29, 2023. CC BY-NC-ND 4.0. Read 2026-10-25.

The values are facts and free to use; this page’s selection and presentation are © 2026 ScienceQuest.