Human Anatomy, Part 2 - K. A. Dyubenko, A. K. Kolomiytsev, Yu. B. Chaykovsky 2008

Special Part
Cardiovascular System, systema cardiovasculare - Special Part
Blood Vessels of the Pulmonary Circulation - Arteries of the Pulmonary Circulation

1. The pulmonary trunk, truncus pulmonalis (Fig. 16 60), is the initial vessel of the lesser, or pulmonary, Circulation. It originates from the so-called conus arteriosus of the right ventricle and transports deoxygenated Blood from the right ventricle to the Lungs. The pulmonary trunk is approximately 4–6 cm in length and about 3,5 cm in diameter. Initially, it courses anterior and then to the left of the ascending aorta, situated between the aorta and the left auricle, entirely within the pericardial cavity. At its origin from the right ventricle, the pulmonary trunk features a semilunar valve that prevents the backflow of venous blood into the right ventricle during diastole. The pulmonary valve consists of three semilunar cusps: anterior, right, and left. About 5–6 cm from its origin, beneath the aortic arch at the level of the IV–V thoracic vertebrae, it bifurcates into the right and left pulmonary Arteries, a. pulmonalis dextra and a. pulmonalis sinistra. This site of division is called the bifurcation of the pulmonary trunk, bifurcatio trunci pulmonalis.

Extending from the point of division of the pulmonary trunk to the concavity of the aortic arch is a connective-tissue cord, lig. arteriosum, which represents the obliterated ductus arteriosus (Botalli) that functioned during the Prenatal period of development.

2. The right pulmonary artery, a. pulmonalis dextra, in terms of its course and size, appears as a direct continuation of the pulmonary trunk. Its length ranges from 3.5–5.5 cm, with a diameter of 2–2.3 cm. It lies posterior to the ascending aorta. Near the right margin of the aorta, the right pulmonary artery is covered by the SUPERIOR VENA CAVA, with the right main bronchus situated anterior to it. At the hilum of the lung, the right pulmonary artery lies anterior and inferior to the right main bronchus.

3. The left pulmonary artery, a. pulmonalis sinistra, crosses anterior to the descending aorta and the left bronchus. At the hilum of the left lung, the left pulmonary artery is initially positioned anterior to the left main bronchus and ascending aorta, and subsequently superior to the superior left pulmonary vein and bronchus.

Within the lung parenchyma, the right and left pulmonary arteries successively branch into lobar, segmental, and interlobular arteries.

** Pulmonary trunk, truncus pulmonalis (PNA); syn. pulmonary artery, a. pulmonalis (JNA, BNA).