The eight extraordinary Qi vessels and the twelve primary Qi channels (meridians) comprise the main part of the channel system. Most of the eight vessels branch out from the twelve primary channels and share the function of circulating Qi throughout the body. These vessels form a web of complex interconnections with the channels. At the same time, each has its own functional characteristics and clinical utility independent of the channels. Traditional Chinese medicine emphasizes the twelve primary organ-related channels and only two of the eight vessels (the Governing and the Conception vessels). The other six vessels are not used very often simply because they are not understood as well as the other channels, and there is still a lot of research being conduct ed on them. Although they were discovered two thousand years ago, little has been written about them. There is a lot of research on the extraordinary vessels being conducted today, especially in Japan, but the results of one researcher often contradict the results that another has achieved.

The eight vessels are called "Qi Jing Ba Mai." Qi means odd, strange, or mysterious. Jing means meridian or channels. Ba means eight and Mai means vessels. Qi Jing Ba Mai is then trans lated as "Odd Meridians and Eight Vessels" or "Extraordinary Meridians (EM)." "Odd" has a meaning of strange in Chinese. It is used simply because these eight vessels are not well understood yet. Many Chinese doctors explain that they are called "Odd" simply because there are four vessels that are not paired. Since these eight vessels also contribute to the maintenance of homeostasis, some times they are called "Homeostatic Meridians." French acupuncturists call them "Miraculous Meridians" because they were able to create therapeutic effects when all other techniques had failed. In addition, because each of these channels exerts a strong effect upon psychic functioning and individuality, the command points are among the most important psychological points in the body. For this reason, they are occasionally called "The Eight Psychic Channels."