The vertically oriented superior vena cava begins posterior to the lower edge of the right first costal cartilage, where the right and left brachiocephalic veins join, and terminates at the lower edge of the right third costal cartilage, where it joins the right atrium (see Fig. 3.86).
The lower half of the superior vena cava is within the pericardial sac and is therefore contained in the middle mediastinum.