Part 6: What are TCM meridians ?
According to Traditional Chinese Medicine (TCM) text Qi flow in a network of meridian channels found all over the body, but despite scientific efforts we have yet to find the modern biomedical equivalent. There are 12 major meridians, supported by 8 extra meridians, 15 collaterals and others. Each of the 12 major meridians is linked internally to an organ and externally with joints, limbs and other superficial tissue.
Unlike the circulatory system meridians are not visible and therefore from a western scientific perspective harder to justify. Western science focuses on anatomical and physiological science to explain the functions of the body. Meridians are not blood vessels, nerves, muscles, lymphatics or connective tissue, but anatomical studies have concluded that acupoints are sites near dense nerve structures, dense vasculature, near lymphatic vessels and have interstitial fluid flow.
Interstitial fluid (or tissue fluid) is a solution that is found in interstitial spaces (or tissue spaces). It is pushed out of capillaries into interstitial spaces due to hydrostatic pressures. It bathes and surrounds cells and tissue. To prevent a build up of interstitial fluid it enters the lymphatic vessels to be transported back into the blood. Overall, the whole interstitium is considered to be four times the volume of blood in the body.
Modern biophysical research on meridians and acupoints show the following;
- Meridians as lines of low electrical resistance and electromagnetic transmission. This has been demonstrated by acupoint finders using the principle of Ohm’s law. Tests show a ten-fold increase in electrical resistance when compared to non-acupoints. Similarly, interstitial fluid has high electro conductively whilst flowing under the skin and when compared to surrounding tissue there is also high sound conductivity.
- Some researchers describe meridians to characteristically have low liquid-pressure resistance, which indicates that the tissue on the meridians is looser.
- Radioactive tracer studies at acupuncture points have helped to show interstitial fluid flow along the meridian lines whilst other similar studies have excluded its flow proximity to be alongside blood vessels.
- The interstitial fluid system is in a state of dynamic equilibrium and depending on a number of factors the fluid pressures (Pi) are not equal at all sites. This suggests that the interstitial fluid is in a constant state of flow due to the varying levels of Pi, and there is a constant need to maintain fluidic equilibrium. Using biorheology techniques the measured speed of flow is found to be much slower than that of blood circulation.
- Another study using magnetic resonance studies demonstrated six specific migration channels of interstitial fluid which again did not correspond to the circulatory or lymphatic vessels instead it followed the pathways of the six Yin TCM meridians, further supporting the flow of interstitial fluid along these meridians.
- Other research has also found that light propagation is more efficient with infrared thermal imaging showing radiant tracks along meridian pathways. There is also significant correlated metabolic activity.
Reasonably conclusions can therefore be made that meridian lines are related to routes of interstitial flow. Further, to this investigators have proposed the most logical location of meridians be the fascia, just below the subcutaneous tissue. Fascia is characteristically a continuous structure found throughout our body similar to meridian pathways, but also typically exhibits the ability of facial transmission of forces which could resolve the question of how the insertion of an acupuncture needle is able to initiate a therapeutic effect.
In Part 7 we will discuss, TCM Meridians & and its link to Fascia.
Part 1: How Does Acupuncture Work?
Part 2: Qi: Vital Energy, Life Force
Part 3: Five Elements Theory
Part 4: Chinese Diagnosis
Part 5: Integrating Western Physiology with TCM Philosophies