By Yitian Ni (Author). By Yitian Ni. Yitian Ni began teaching and practicing TCM in the late 1960’s, both in the PRC and the U.S.A. It delves into the components of the channels and collaterals and the characteristics of the channel system, providing descriptives of the twelve channel and extraordinary channel systems that include the key points, pathway, associated organs and points, physiology, pathology, clinical applications, and divergent, tendinomuscular, and collateral channels.