right brachiocephalic vein [AS, riht + Gk, brachion, arm, kephale, head] , a vessel, about 2.5 cm long, that starts in the root of the neck at the junction of the internal jugular and the subclavian veins on the right side and descends vertically from behind the sternal end of the clavicle to join the left brachiocephalic vein and form the superior vena cava. The right brachiocephalic vein, like the left, receives various tributaries, such as the vertebral vein, the internal thoracic vein, and the inferior thyroid vein. Compare left brachiocephalic vein.