A rare combination of variations of superior mediastinal vessels

Superior mediastinum contains many important vessels and tubes, variation of one may affect the other. Left brachiocephalic vein crosses arch of the aorta and its branches superficially. Arch of the aorta from its convex superior aspect usually provides brachiocephalic, left common carotid and left subclavian artery from the right to left. Left subclavian artery continues as axillary artery and becomes the only major source of blood for the upper limb. First part of the subclavian artery on the left side usually provides vertebral, internal thoracic, thyrocervical trunk and costocervical trunk. There is an azygos venous system in the posterior thoracic wall which consists of azygos, hemiazygos and accessory azygos veins. Hemiazygos and accessory azygos veins usually drain into azygos vein at the level of 8th and 7th thoracic vertebra respectively [1].