CT Pulmonary Angiography > PA Anatomy > Pulmonary Artery Anatomy

Pulmonary Artery Anatomy

The main pulmonary artery (MPA) is intrapericardial and courses posteriorly and superiorly from the pulmonic valve. It divides into the left pulmonary artery (LPA) and right pulmonary artery (RPA) at the level of the fifth thoracic vertebra. The RPA is longer than the LPA and crosses the mediastinum, sloping slightly inferiorly to the right lung hilus. The LPA represents the continuation of the MPA.

Segmental and subsegmental pulmonary arteries generally parallel segmental and subsegmental bronchi and run alongside them. This is in contrast to the course of most pulmonary veins, which run independently of bronchi within interlobular septa. The segmental arteries are named according to the bronchopulmonary segments that they feed, and we follow the Jackson and Huber classification in this description. However, the proximal portions of the arteries to the posterior subsegment of the left upper lobe and the lingular arteries can run independently of their respective bronchi for short segments. Also, there are frequently accessory arteries from neighboring segments, particularly in the right upper lobe. Segmental and subsegmental pulmonary arteries vary considerably in the location of their origins, in whether they arise as common trunks with other arteries or as separate arteries, and in their number.

This diagram may help simplify the segmental anatomy of the lung and the pulmonary arteries. It is only meant to simplify the anatomic relation of segments to one another within each lobe and not their exact anatomic locations.