These vessels merge to form the superior vena cava. The brachiocephalic veins are the major veins returning blood to the superior vena cava. The superior and inferior vena cava are collectively called the venae cavae.They are the veins that return deoxygenated blood from the body into the heart.Hope this is the answer you were looking for.he superior and inferior vena cava are collectively called the venae cavae. They are the veins that return deoxygenated blood from the body into the heart. Hope this is the answer you were looking for.