In Chinese medicine the Spleen is the primary organ of digestion. It receives the pure products of digestion of food (by the Stomach and Intestine) and transforms it into essential energy, which it is also responsible for raising to the Lung. The Spleen also transforms and moves Water around the body, corresponding to some of the functions of the lymphatic system. The Spleen rules the muscles, connective tissue, fat tissue and and the four limbs; their power depends on its strong function. Harmonious Spleen is reflected in the five senses and the appearance and sensitivity of the mouth, especially the lips and mouth cavity.
The Chinese notion of the Spleen does not correspond to the physical organ by the same name in western medicine. The Chinese Spleen combines the spleen with the pancreas and what is known as the reticulo-endothelial system (RES): the network of reticular connective tissue and endothelium that forms various anatomical structures including the lymphatic tissues and organs in the body that comprise the immune system, such as tonsils and thymus, and the red bone marrow, the copper star cells of the liver and the mucous membranes of the intestine.
The Spleen is the Yin Organ of Earth in the body. Its corresponding Yang Organ is the Stomach.