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Pulmonary trunk

Pulmonary trunk [truncus pulmonalis (PNA); synonym: pulmonary artery (arteria pulmonalis, BNA), arterial vein Galen] - an artery that carries venous blood from the right ventricle of the heart to the lungs. The projection of the vessel on the chest wall in front: II intercostal space or III rib to the left of the sternum.

Anatomy
The pulmonary trunk begins in the pericardial cavity from the cone of the right ventricle. At first it lies in front and then to the left of the ascending aorta.

At the level of the body of the IV thoracic vertebra, the pulmonary trunk is divided into the right and left pulmonary arteries going into the lungs (aa. Pulmonales dext. Et sin.) (See Lungs).

The length of the pulmonary trunk is 4-6 cm, the diameter is 3-3.5 cm. The pulmonary trunk is found along a constantly existing small vein surrounding its mouth; in this place, the right and left ears of the atria are adjacent to the pulmonary trunk, and the left atrium is behind and below. At the beginning of the pulmonary trunk is a valve - valva trunci pulmonalis, which prevents reverse flow; blood during diastole.

The angle of division of the pulmonary trunk often blunt, open up and to the right. From the trachea, the pulmonary trunk is separated by loose paravasal fiber, in which the extracardiac nerve plexus is located. The length of the right pulmonary artery is about 4 cm, the diameter is 2-2.5 cm, the length of the left is 3.3 cm, and the diameter is 1.8 cm. The right and left pulmonary arteries are divided into lobar and segmental branches, corresponding to the lobes and segments of the lungs (Fig. 1).


Fig. 1. The ratio of the bronchi and the branches of the pulmonary arteries (rear view): 1 - truncus pulmonalis; 2 - a. pulmonalis dext; 3 - a. pulmonalis sin.

The pulmonary trunk belongs to elastic type arteries. In the middle shell, it is distinguished by longitudinal and circular layers of smooth muscle fibers; its basis is a dense network of elastic fibers. At the beginning of the pulmonary trunk, the annular fibers form a kind of sphincter.

The blood supply to the wall of the pulmonary trunk is carried out by the coronary and bronchial arteries.

Innervation: vagus nerves, branches of sympathetic trunks, phrenic nerves, and fibers of the spinal nodes C V —Th V.

Histology - see Arteries.