Brachiocephalic trunk

The first and largest branch of the arch Arises opposite the centre of the manubrium sterni In front of the trachea As it ascends it inclines to  the right to reach the posterior aspect of the right sternoclavicular joint. There if bifurcates into right subclavian and right common carotid arteries. Between it and the manubrium are the left brachiocephalic vein, thymic remnants and lower attachments of sternothyroid and sternohyoid. Upper portion is medial to the right brachiocephalic vein The right vagus is lateral to it  then passes behind it to reach the right side oft he trachea.