Superior vena cava (anatomy)

The superior vena cava is formed proximally by the union of the right and left brachiocephalic veins within the superior mediastinum. This occurs at the level of the right first costal cartilage. From this point, the SVC runs for about 5-7cm inferiorly, slightly medially and anteriorly. It ends at the superior vena caval orifice in continuity with the right atrium deep to the third right costal cartilage in the middle mediastinum. It becomes ensheathed by pericardium superior to this point. Posteriorly, at the level of the second costal cartilage, the azygous vein arches anteriorly over the root of the right lung to merge with the posterior surface of the SVC.

The relation of the SVC include:

• superoposterior and medially: the trachea with the right vagus nerve passing inferiorly on its surface
• posteroinferiorly: the right azygous vein arching superior to the right lung root
• laterally: right phrenic nerve running inferiorly with mediastinal parietal pleura more laterally
• superomedially: arch of aorta
• inferomedially: pericardium separated by transverse sinus of heart from ascending aorta
• superiorly: brachiocephalic veins
• inferiorly: right atrium