Final answer:
The intercostal nodes drain into the azygos vein and return blood to the heart via the pulmonary veins.
Step-by-step explanation:
The intercostal nodes are lymph nodes located in the intercostal spaces between the ribs. These nodes play a role in the lymphatic drainage of the thoracic (chest) region. Specifically, the intercostal nodes receive lymphatic vessels that drain various structures in the thoracic cavity, including the muscles, skin, and parietal pleura (the outer layer of the membrane surrounding the lungs).
From the intercostal nodes, the lymphatic drainage proceeds to higher levels in the lymphatic system. The lymph ultimately reaches the bronchomediastinal lymph trunks, which are larger collecting vessels. These trunks then converge to form the thoracic duct on the left side of the body or the right lymphatic duct on the right side. The thoracic duct and the right lymphatic duct are the two main channels through which lymph is returned to the bloodstream.