intercostal node, a node in one of three groups of thoracic parietal lymph nodes situated near the dorsal parts of the intercostal spaces. The nodes are associated with lymphatic vessels that drain the posterolateral area of the chest. The efferent vessels from the nodes in the caudal four or five spaces form a descending trunk that opens into the dilated origin of the thoracic duct. The efferent vessels from the nodes in the upper intercostal spaces on the left side connect with the thoracic duct. Those on the right side end in the right lymphatic duct. Compare diaphragmatic node, sternal node. See also lymphatic system, lymph node.