The azygos venous system is highly variable in terms of its origin, course, communications, tributaries and termination of the associated veins: this study aimed to classify these anatomical variations. Thirty Thiel-embalmed cadavers aged 4898 years (18 female, 12 male) were examined. The vertebral level of termination and diameter of the azygos, hemiazygos, accessory hemiazygos and the left superior intercostal veins were determined, as well as the termination level of the right superior intercostal vein. The azygos system was classified into 3 types; primitive (type 1), transitional (type 2) and unicolumnar (type 3). Type 2 was further divided into 5 subgroups (A to E) according to the number of retroaortic communications. Type one was observed in 3 %... |