A. The lymph vessels from the anterior parts of the spaces drain into anterior intercostal/internal mammary lymph nodes. The efferent from these nodes unify with those of tracheobronchial and brachiocephalic nodes to create the bronchomediastinal trunk, which drains into subclavian trunk on the right side and thoracic duct on the left side.
B. The lymph vessels from the posterior parts of the spaces drain into posterior intercostal nodes. The efferent from the posterior intercostal nodes of lower 4 spaces unify to create a slim lymph trunk, which descends and drain in the cysternachyli. The efferent from posterior intercostal nodes of upper spaces drain into right lymphatic duct on the right side and thoracic duct on the left side.
A. Posterior intercostal nodes.
B. Anterior intercostal/internal mammary (parasternal) nodes.
The posterior intercostal nodes are found in the posterior part of the intercostal spaces on the necks of the ribs.
The anterior intercostal nodes is located along the course of internal thoracic (mammary) artery.