Meridian system composition
Meridians include the twelve meridians, Eight Veins of Strange Meridians, the twelve meridians and Fifteen Collaterals. The twelve meridians is the trunk of meridians, which is "hidden in the official organs (viscera) and collateral in the branches" (On Ling Shu Hai). The twelve meridians is an expert branch of the twelve meridians on chest, abdomen and head. Eight strange meridians have special distribution and certain functions. Fifteen collaterals refer to the the twelve meridians of the human body, plus Ren meridian in front of the trunk, Du meridian behind the trunk, and spleen collateral on the side of the trunk, totaling fifteen collaterals. The twelve meridians is divided into lung meridian of hand Taiyin, large intestine meridian of hand Yangming, stomach meridian of foot Yangming, spleen meridian of foot Taiyin, heart meridian of hand Shaoyin, small intestine meridian of hand Taiyang, bladder meridian of foot Taiyang, kidney meridian of foot Shaoyin, pericardium meridian of hand Jueyin, triple energizer meridian of hand Shaoyang, gallbladder meridian of foot Shaoyang and liver meridian of foot Jueyin. The twelve meridians is the main body of the meridian system, so it is called "Zheng Zheng".