In traditional Chinese medicine (TCM), the meridians and collaterals are vital channels within the body that circulate qi and blood and transmit information, closely connected to the zang-fu organs, limbs, five sense organs, and nine orifices. The function of the meridian system extends beyond the mere transport of nourishment and energy — it also serves as an important bridge between the human body and the external environment. The structure of the meridians is extraordinarily refined, like an invisible network that pervades the entire body, closely linking all the zang-fu (viscera and bowels) together.

The Chapter Er Shi Ba Nan (The Twenty-Eighth Difficult Issue) of Nanjing (The Classic of Difficult Issues) describes the operation of the meridians: “Like the sage who designed irrigation channels — when the channels overflow, the water flows into the deep lakes, and the sage cannot confine its passage.” This vivid metaphor reveals that the meridians function like rivers, ceaselessly supplying qi and blood and circulating among the zang-fu organs. When the meridians are unobstructed, qi and blood flow freely, and the body maintains its vitality and health. Conversely, when the meridians are blocked and qi and blood become stagnant, various diseases and discomforts may arise.

The meridians are divided into the twelve regular meridians and the eight extraordinary meridians. The twelve regular meridians are like major rivers, each corresponding to different zang-fu organs, while the eight extraordinary meridians function as tributaries, serving to regulate and redirect the flow. Along each meridian are a number of specific acupoints — convergence points of the meridians with particular functions. Through the stimulation of these acupoints, the flow of the meridians can be adjusted and the circulation of qi and blood promoted, thereby achieving health preservation and therapeutic effects.

In TCM treatment, acupuncture and moxibustion therapy utilises these meridian pathways for regulation. By needling acupoints, qi and blood are kept flowing smoothly to promote health. The success of this therapeutic method stems precisely from a profound understanding and application of the meridian system.

The meridians are not merely physiological structures; they are also a vital cornerstone of physical and mental well-being. Maintaining their patency helps preserve overall health and balance.