The spleen is located in the left upper abdomen, between the fundus of the stomach and the diaphragm in the left quaternary rib area, on the deep side of the 9th to 11th ribs, with the long axis coinciding with the 10th rib. The spleen is not palpable below the left costal arch when normal. The position of the spleen may change with respiration and body position, being lower when standing than when lying down. The spleen can be divided into the dirty and diaphragmatic sides. In the center of the dirty side there is the splenic hilum, a place where blood vessels and lymphatic vessels enter and exit. On the dirty side, the spleen is adjacent to the fundus of the stomach, the left kidney, the left adrenal gland, and the colon. In splenomegaly, the splenic notch is a sign of palpation. The spleen is the largest lymphoid organ in the organism, with roles in blood storage, hematopoiesis, removal of senescence-damaged red blood cells, and immune response. When ischemia and hypoxia occur in the organism, the spleen rapidly transports the stored blood back into the circulation and relieves the condition.