The Brachiocephalic veins
are the union of the subclavian and internal jugular veins. The right brachiocephalic
vein is formed behind the right sternoclavicular joint and descends vertically.
The left brachiocephalic vein passes almost horizontally across the superior
mediastinum to join the right vein at the lower border of the first right costal
In children and infants the left brachiocephalic vein develops and courses in the lower neck rather than the superior mediastinum.