Meridians and Channels in Acupuncture: The Twelve Main Channels and Extraordinary Vessels

A traditional map

In acupuncture, meridians (also called channels) are the pathways along which acupuncture points are arranged. A researcher in the field describes meridians as traditionally believed to be channels connecting the surface of the body to the internal organs. [1] This is a traditional framework, not an anatomical finding. For the wider concept see Meridians and Collaterals in TCM and Qi, Yin and Yang, Five Phases and Meridians.

The twelve main channels

The Huangdi Neijing (Yellow Emperor's Inner Classic), a text from the period 475 to 225 BCE, describes the pathways of main, collateral and "curious" vessels. [2] A 2019 comparison of early Chinese and Western medicine says the Neijing describes twelve channels called meridians, including their distribution and physiological functions, and that each of the twelve belongs to a respective organ. [3]

In practice, point-location papers name the channels by short codes, such as Lung (LU), Large Intestine (LI), Pericardium (PC), Bladder (BL) and Gallbladder (GB). [4][5]

Extraordinary vessels, Governing and Conception

Once the theory of meridians and collaterals was set out, the system grew to include twelve tendinomuscular meridians, twelve divergent meridians, twelve principal meridians and eight extraordinary vessels. [3] Two of the extraordinary vessels, Ren mai and Du mai (commonly translated Conception Vessel and Governing Vessel), have their own acupuncture points along their paths. [6] A study correlating head zones with channels counted 14 channels with their own points: the 12 main channels plus Ren and Du. [6] That study chose these 14 because they have their own points.

How the system developed

Meridian theory was not written at once. A review of a history of the theory says that in the Qin and Han dynasties six meridians were developed from six types of qi, and and that eleven meridians, later twelve, were structured. [7] For the history see the History of Acupuncture and Acupuncture in China, Japan, Korea and Beyond. Styles differ by region on how heavily they rely on channels; see Japanese Acupuncture and Meridian Therapy.

What studies have looked for

1. Do points and meridians conduct electricity differently?

   Insufficient evidence

   A systematic review of 16 articles found 5 of 9 point studies and 7 of 9 meridian studies reported lower impedance, but studies were poor in quality and small, and evidence does not conclusively support the claim [8]

2. A careful follow-up in 23 people

   Insufficient evidence

   Impedance was lower along the Pericardium meridian but not the Spleen meridian; the authors suggest needle contact with connective tissue may explain it [9]

3. Do points follow connective tissue planes?

   Promising but limited

   About 80% of point sites matched intermuscular or intramuscular planes in human arm sections [1]

4. Could meridians be fascia, vessels or nerves?

   Proposal only

   One 2025 clinician proposes Bladder and Gallbladder are myofascial meridians and Lung and Pericardium may be blood vessels or nerves [4]

5. Are meridians separate tissues?

   Insufficient evidence

   A 2024 paper says there is no clear evidence points and meridians are separate organs or specific tissues [10]

Why it matters for care

Whether meridians exist as structures is a different question from whether a treatment helps a particular problem, which trials answer condition by condition. See How to Read an Acupuncture Study and Acupuncture Points Explained.