Overview
The superior vena cava is a large, valveless vein that returns venous blood from the upper body (above diaphragm, except the heart) to the right atrium.
Origin
- Union of left and right brachiocephalic veins at level of T3, posterior to the right first intercostal space
- Left brachiocephalic vein crossing midline to join right brachiocephalic vein
Course
- Descends vertically down superior mediastinum with slight posterior course, to the right of the aorta and trachea
- Enters the middle mediastinum and becomes surrounded by the fibrous pericardium.
Termination
- It terminates by empting into the superior aspect of the right atrium at the lower edge of right third costal cartilage after a short intrapericardial course
Tributaries
- Right and left brachiocephalic veins (T3) – draining head and neck, and upper limbs
- Azygous vein (T4) – drains the majority of the posterior chest wall and upper lumbar regions
- Small veins draining; pericardium, oesophagus and other mediastinal structures
Relations
- Left: arch of aorta, trachea
- Right: pleura, right upper lobe, right phrenic nerve
- Anterior: thymus (if present)
- Posterior: Azygous vein, right pulmonary artery, right pulmonary vein, right main bronchus
- Superior: brachiocephalic veins, superior thoracic aperture, lymph trunks
- Inferior: heart, right atrium, inferior vena cava
Anatomical Variants
- Absent SVC (Brachiocephalic veins drain directly into RA)
- SVC duplication (Left sided SVC with normal right SVC)
- Left sided SVC without right SVC
- Azygous continuation of IVC as tributary