The internal thoracic lymph nodes are a pair of longitudinally-linked chains of nodes on either side of the sternum. They are sited in the anterior section of the intercostal spaces level with the costal cartilage and deep to the intercostal muscles.
Usually, there are 4-5 nodes in total on each side. Typically, these are positioned in the first to third interspaces and the fifth or six interspace.
The internal thoracic nodes receive efferent lymphatic vessels from:
anterior mediastinal nodes anterior diaphragmatic nodes; a possible route for spread of hepatic malignancy superficial and deep lymphatics of the medial side of the breast anterior end of the intercostal spaces The internal thoracic nodes drain to anterosuperior mediastinal nodes. From here, the bronchomediastinal lymphatic trunk conveys lymph to the great veins within the neck.