APPLIED ANATOMY OF THE AZYGOS VENOUS COURSE, VALVES AND THE CONNECTIONS BETWEEN AZYGOS VENOUS SYSTEM AND INTERNAL VERTEBRAL VENOUS PLEXUS

In most anatomical textbooks and literatures, the azygos vein has been described as ascending on the right side of the vertebral column, but this description only coincides with the results of our 48 children's series. In 84 adults' specimens, a part of azygos vein course crossing midline appeared in 72.63 %. The possible courses of the displacement of the azygos vein to the left were related to the displacement of the aorta and the development of right posterior lung in the azygos-esophageal recesses. Among 66 specimens single valves were found in the azygos vein in 47 oases (83.9%), two valves, in 3 cases (5.4%) and no valves, in 6 oases (10.7%). Valves were mainly located at the middle third (48.9%) and posterior third (23.4%) of the azygos arch.. The connections between the azygos system and the internal vertebral venous system (IVV) were observed with the methods of venous casts and venography. Azygos system was connected to the IW by the way of intervertebral veins, the posterior group of external vertebral veins and the basic vertebral veins.