The accessory cephalic vein is the name for a variable vein that travels alongside the forearm's radial or thumb-side border. The vein passes this way in order to get to the cephalic vein that is close to the elbow. The cephalic veins are big veins that go up the arm's lateral side. They start at the hand and go all the way to the shoulder. When the veins arrive at the shoulder, they drive deep into the tissues and then drain into the axillary vein. When the cephalic veins and the axillary vein merge together, they form the subclavian vein. The subclavian vein ultimately drains into the superior vena cava. Within the elbow's bend, a medial cubital vein arises out of the cephalic veins and then transfers to the basilic vein. The basilic vein is frequently used for blood samples. The accessory cephalic vein generally emerges out of a tributary plexus of the forearm, but in some cases it also can arise out of the dorsal venous network.