Interkostalvenen

Interkostalvenen, also known as intercostal veins, are a series of veins located between the ribs in the thoracic cavity. They run alongside the intercostal arteries and nerves in the intercostal spaces, collecting deoxygenated blood from the chest wall muscles, pleura, and the outer parts of the lungs. There are typically eleven pairs of intercostal veins, corresponding to the eleven pairs of ribs. The uppermost vein in each space is called the superior intercostal vein, and the lower veins are generally referred to by their corresponding rib number, such as the second intercostal vein.

The drainage pattern of the intercostal veins varies. The upper intercostal veins (typically the first to fourth or fifth) usually drain into the brachiocephalic vein or the superior vena cava. The lower intercostal veins, however, have a more complex drainage system. The right lower intercostal veins drain directly into the azygos vein, which then empties into the superior vena cava. On the left side, the lower intercostal veins (typically the lower six) drain into the hemiazygos vein, which often crosses to the right side to join the azygos vein, or may drain directly into the left brachiocephalic vein. This venous network plays a crucial role in returning deoxygenated blood from the thoracic wall to the central circulation.