5.2. Veins That Drain Inferiorly and Medially
The basic organisation of these veins is as follows (see the accompanying diagram too):
- The external jugular vein drains into the subclavian vein. The subclavian vein then unites with the internal jugular vein to become the brachiocephalic vein. This is the case for both sides of the thorax. The brachiocephalic veins of both sides unite to form the superior vena cava. The superior vena cava drains into the right atrium of the heart.
- There is asymmetry between the left and right brachiocephalic veins: the left passes across the midline of the body, running superior to the aortic arch. The right brachiocephalic vein remains on the right side of the body. As such, the left brachiocephalic vein is considerably longer than the right.
- On each side, although not shown in the diagram, the supreme/highest intercostal vein drains the 1st posterior intercostal vein into the brachiocephalic vein (although sometimes it drains into other veins).
- On each side of the body there is a superior intercostal vein. This drains the 2nd, 3rd and 4th posterior intercostal veins into...
...the left brachiocephalic vein on the left and…the azygous vein on the right.
- The subclavian vein on each side drains most of the blood from the upper limbs.