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Pulmonary trunk

Recommended video: Pulmonary arteries [01:29]
Anatomy and function of the left and right pulmonary arteries.
Pulmonary trunk (Truncus pulmonalis)

The pulmonary trunk is a short artery transporting deoxygenated blood from the heart towards the lungs. Some authors refer to this vessel as the main pulmonary artery, or simply the pulmonary artery.

The pulmonary trunk arises from the base of the right ventricle of the heart. After passing behind the ascending aorta, it splits up into the left and right pulmonary arteries to provide blood for oxygenation in the lungs.

This article will discuss the anatomy and function of the pulmonary trunk.

Key facts about the pulmonary trunk
Origin Conus arteriosus of right ventricle
Branches Left and right pulmonary arteries
Supply Delivers deoxygenated blood to the lungs via pulmonary arteries
  1. Origin and course
  2. Relations
  3. Branches and supply
  4. Clinical relations
    1. Patent ductus arteriosus (PDA)
  5. Sources
+ Show all

Origin and course

The pulmonary trunk has a length of only about 5 cm. It is the direct continuation of the right ventricular outflow tract and starts at the conus arteriosus of the right ventricle. Initially located anterior to the ascending aorta, the vessel runs posteriorly and crosses the ascending aorta to the left.

After its short course, the pulmonary trunk splits into the left and right pulmonary arteries at the level between the T5 and T6 vertebrae. The left pulmonary artery is commonly a direct continuation of the pulmonary trunk's course, while the right pulmonary artery arises almost at a right angle.


The pulmonary trunk is covered by pericardium and lies in a common sheath with the ascending aorta. Its lumen contains the pulmonary valve which permits the blood to flow from the right ventricle to the pulmonary trunk. The cusps of the pulmonary valve form mild dilations in the pulmonary trunk wall called pulmonary sinuses.

The pulmonary trunk is connected to the descending aorta via the ligamentum arteriosum, a remnant of the obliterated ductus arteriosus (ductus Botalli). In the developing fetus, the ductus arteriosus transports blood directly from the pulmonary trunk into the aorta and bypasses the fetal lungs.

Branches and supply

The pulmonary trunk terminates in the two pulmonary arteries.

  • The right pulmonary artery runs underneath the aortic arch and passes behind the superior vena cava to the right lung hilum.
  • The left pulmonary artery is shorter than its right counterpart and arches over the left main bronchus before reaching the left lung.

Test your knowledge on structures of the thorax at the level of the pulmonary veins with this quiz.

Expand and test your knowledge with our learning materials to master the surrounding structures of the heart and the main structures of the cardiovascular system.

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