Overview
The venous drainage of the thoracic wall drains deoxygenated venous blood from the periphery of the thoracic cage back into the systemic circulation. It generally follows arterial supply, and consists of anterior and posterior intercostal veins running transversely in the subcostal space, draining into an anterior and posterior system of vertical veins (internal thoracic and azygous vein).
Structure
Each intercostal space has one posterior and two anterior intercostal veins accompanying the arteries of the same name:
Anterior intercostal veins
- Travels anteriorly within the costal groove in the inferior margin of the ribs
- Intercostal veins are located superiorly in the neurovascular bundle (superior to inferior: vein, artery, nerve)
- Drain into the internal thoracic veins or musculophrenic veins, which then drain into the brachiocephalic veins
Posterior intercostal veins
- First intercostal space – drains into supreme intercostal veins and then into brachiocephalic veins
- 2nd – 4th intercostal veins – drains into superior intercostal vein, which empties into azgous vein on the right, brachiocephalic vein on the left
- 5th – 12th drain into azygous system – azygous vein on the right, hemi-azygous vein on the left
Perforating veins
- Veins pierce through internal intercostal muscles of upper 6 intercostal spaces to drain into internal thoracic vein.
Anatomical Variants
- Superior intercostal veins may additionally drain the 4th intercostal space
- Accessory hemiazygous vein may drain the left 8th intercostal space posteriorly.