Meridians and Collaterals as a Traditional Framework

A traditional map of the body

In traditional Chinese medicine (TCM), meridians (jing) and collaterals (luo) are the channels along which qi and blood are said to travel, linking the body surface with the internal organs. A review of the Huangdi Neijing (Yellow Emperor's Inner Classic) says the text describes the pathways of main, collateral and "curious" vessels and the circulation of blood and qi. [1] A researcher in the acupuncture field describes meridians as traditionally believed to be channels connecting the surface of the body to internal organs. [2]

This is a traditional framework. Acupuncture points are described as lying along these channels, which is why the meridian map is used in acupuncture. For the practice itself and its evidence see What Is Acupuncture? and Acupuncture Methods.

How the idea developed

The meridian system was not written down all at once. A review of a book on the history of the theory says meridians evolved over time: in the Qin and Han dynasties six meridians were developed on the basis of six types of qi, and in terms of "six types of qi and five elements" five zang organs, six fu organs and eleven meridians were structured. It then describes twelve meridians being composed by correspondence with celestial cycles. [3] A history of body diagrams adds that illustrations focused on meridian theory used zang-fu organ metaphors to explain acupuncture taboos. [4] For the organs see Zang-Fu; for qi see What Is Qi?; for the framework as a whole see Qi, Yin and Yang, Five Phases and Meridians.

What studies have looked for

Researchers have tried to find a physical basis for meridians for decades. The main lines of work, and what they found, are below. The strength labels use this site's evidence scale.

Modern interpretations and proposals

Several recent papers propose that meridians might map onto known structures. These are proposals, not established facts:

• An acupuncture article in the Journal of Alternative and Complementary Medicine argued that failing to use clear terminology and to rigorously investigate acupuncture points has hindered acupuncture's legitimacy as an evidence-based therapy, and called for rigorous tests of their specificity and possible biological basis. [9]
• A 2025 paper on "structure-based" acupuncture suggests some meridians correspond to fascia chains, blood vessels or nerves, and says some meridians such as Bladder and Gallbladder are myofascial meridians while the Lung and Pericardium may be vessels or nerves. [10] This is one clinician's model.
• A 2026 hypothesis paper proposes that the traditional sanjiao-mocou concept is analogous to the fascial-interstitial system, which it says would provide a testable model of meridians. [11]
• A 2026 proposal would treat meridians as functional networks in a body-based coordinate system, shifting research from debates about what they are to testable questions about how stimulation effects are spatially distributed. [12]

An author of one paper on the body as an electronic circuit states plainly that there is no clear evidence that acupuncture points and meridians are separate organs or specific tissues. [13] In summary: the meridian system is a long-standing map used in practice, and no one has shown a single anatomical structure that corresponds to it.

Does it matter for acupuncture?

Whether meridians exist as structures is a different question from whether acupuncture or acupressure helps a specific problem. Trials decide the second question, and the answer differs by condition: see Acupuncture for Back and Neck Pain, Acupressure and TCM Evidence by Use. An overview of 104 Cochrane reviews on TCM found only 5 with overall positive conclusions, 42 with insufficient evidence and 54 without firm conclusions. [14] For general guidance on reading trials see Understanding Evidence.