<prompt> True about brachiocephalic vein is all exceptFormed behind sternoclavicular jointLeft vein is longerRight runs veicalRight vein unite at 1st costal cailage  <response>: Right brachiocephalic vein joins left brachiocephalic vein at 1st costal cailage to form superior vena cava. this is present in the superior mediastinum Ref: Grays 38ep1026 