The Meridian system consists of meridians and collaterals,which connect to the viscera internally and to the tendons, muscles and skin externally.
Thus, Chapter 33 in Spirit Pivot states: "Internally,meridians connect with the viscera, and externally with the limbs and joints."
Meridians can be divided into two types: regular meridians and extra meridians. The regular meridians have twelve branches, including the three yin meridians of the hands and the feet, and the three yang meridians of the hands and the feet. These are generally termed "the twelve regular meridians." They are the main pathways in which qi and blood circulate. The twelve regular meridians originate from and terminate at certain areas, and have specific courses and sequences in their circulation. There is a rule in their distribution over and passing through the trunk and limbs, and they pertain to and connect with the viscera directly in the interior of the body.
There are eight extra meridians: Du (Governor Vessel), Ren (Conception Vessel), Chong, Dai, Yinqiao, Yangqiao, Yinwei, and Yangwei, collectively termed "the eight extra meridians. "They have functions of governing, connecting, and regulating the twelve regular meridians. According to the book General Collection for Holly Relief, the differentiation between regular and extra meridians is as follows: "Meridians can be divided into the extra and the regular, the twelve meridians belong to the regular, and the eight meridians are different from the regular, as they go along additional courses. The qi and blood of the human body run along the twelve regular meridians and flow into the extra meridians while the regular ones are full. "
The twelve divergent meridians spread from the regular meridians, starting from four limbs and transversing the deep portion of the viscera, and emerging from the superficial position of the neck and nape. After splitting from their original meridians and running through the interior of the body, the divergent meridians of the yang meridians return to their yang meridians. The divergent yin meridians meet with the yang meridian, of the interior-exterior meridians. The main functions of the twelve divergent meridians are to strengthen interconnection between the two interior-exterior meridians in the twelve regular ones, and to replenish the regular meridians, as the divergent meridian can reach the organs and body areas where some regular meridians can not traverse.
The collaterals are smaller branches of meridians, classified as the divergence collaterals, superficial collaterals and small collaterals. The divergence collaterals are the larger of the collaterals.
The twelve regular meridians and Du, Ren Meridians have large collaterals each and along with the great collateral of the spleen, are together called. "The fifteen divergence collaterals." Their main function is to strengthen the communication between interior-exterior meridians located on the body's surface. The superficial collaterals run along the surface of the body and are often visible, while the small collaterals are mini and beyond observation. Together, they function in transmitting qi and blood and in readjusting the nutrient and defence-qi.
The meridian tendon regions and the skin areas comprise the twelve regular meridians, along with the tendon fascia, muscles, and body surface. The meridian theory holds that the meridian tendon is the system whereby the meridian-qi knots, gathers, scatters, and connects with the tendons, muscles and joints. This is affiliated with the regular meridians and together is therefore called the twelve meridian tendon regions. It functions in connecting limbs and tissues, as well as controlling joint movements.
The skin of the body provides the position through which the functional activities of the twelve regular meridians reflect themselves and where meridian qi is distributed. All the skin areas can be divided into twelve parts which respectively correspond to the twelve meridians, termed: "the twelve skin areas."
