To the X-ray characterization of the accessory pulmonary lobe of the azygos vein (lobus azygos)

The occurrence of an anomaly of the upper lobe of the right lung is due to an unusual passage of the azygos vein. In the process of embryonic development, the azygos vein is initially located in the posterior mediastinum to the right of the spine, reaches the level of the IV-V thoracic vertebra, here it bends through the root of the right lung and flows into the superior vena cava.