It is the central control to digestion and muscle development. The spleen is believed to absorb the nutrients from food and then to stimulate the dispersal of this "food essence" through the body.
If the spleen Qi is strong, the digestion and distribution of nutrients work well and the body is healthy.
If it is weak, the tissues will become malnourished.
The spleen performs the same function with water extracted from food. It sends this extraction through the body to reach the kidneys. Due to this association with nutrition, the spleen is said to be responsible for building strong limbs and well-developed muscles. 医学.全在线www.med126.com
It also controls the limbs and flesh. Therefore, muscular aches and pains or weakness can suggest a deficiency in spleen. Strong spleen Qi is needed to keep blood flowing in the vessels - if it is weak then there may be haemorrhages or subcutaneous bleeding.
The spleen is also involved in mental activities and is specifically responsible for "Yi". "Yi", in Chinese, refers to intention, willpower, determination, or an awareness of the possibilities open to us to make changes in our lives.
The spleen and stomach are very closely associated - more so than the other Zang-Fu pairings, and the terms are sometimes used interchangeably.
The stomach rules "descending" activities while the spleen controls "ascending" actions. Let me elaborate further: