parietal lymph node, any one of the small oval glands that filter the lymph coursing through the lymphatic vessels in the walls of the thorax or through the lymphatic vessels associated with the larger blood vessels of the abdomen and the pelvis. The parietal lymph nodes of the thorax include the sternal nodes, intercostal nodes, and diaphragmatic nodes. The parietal lymph nodes of the abdomen and pelvis include the common iliac nodes, epigastric nodes, external iliac nodes, iliac circumflex nodes, internal iliac nodes, lumbar nodes, and sacral nodes. See also lymph, lymphatic system, lymph node.