Oriental Medical therapies use pathways, called meridians or channels, to direct energy and nutrients throughout the body. This is an ancient view of the body, one that international efforts of modern science are only recently beginning to successfully measure with technology.
The ancient Chinese used metaphor to explain the nature and function of the body's meridians: Let's consider a river. A river is more than just the water in the river; it includes the riverbed, the riverbank, the plants and animals living in the river, as well as the plants and animals surrounding the riverbank. A river is a complex of moving parts that all work together to nourish and be nourished by its larger environment.
Likewise, the meridian network is a system of pathways through which the vital energy and nutrition of the body move. Meridians can be thought of as spacial regions within which one might find nerves, blood vessels, and lymphatic circulation. In respect they serve to unify or integrate the anatomical structures associated with particular internal organs. They act as pathways not only for the flow of substances around these anatomical structures, but also for the flow within the structures. For example, the pathway known as the Lung Meridian includes certain muscle groups, nerves, and lymphatic vessels on the forearm, throat, and chest. It also includes the nose, and enters the Lung organ itself. Healthy circulation within and around these structures will fall within the scope of what Chinese Medicine calls "the Lung Meridian."
An additional aspect of a meridian is the fascial plane. If we look closely at the point locations along each meridian, they fall along lines, or planes, of fascia - the connective tissue that wraps and integrates muscles. Studies[1],[2],[3],[4] have examined the effect of acupuncture stimulation of these planes, finding that needle insertion and manipulation stimulates mechanicoreceptors in the fascia, and creates a cascade of effects along that fascial plane. Considering that fascial planes are contiguous throughout the body, meaning that they are found in and connect all the regions of the body to each other, they are an important part of how those regions of the body “speak” to one another. However, it is important to remember, like the riverbed is only one aspect of a river, fascial planes are only one aspect of the meridian system.
Another part to consider is the muscular system. Let’s say a patient comes in with “tennis elbow,” and I find that there is significant muscle shortening around the elbow and forearm. Informed by my training, I insert needles to release trigger points on the flexor carpi radialis brevis and the extensor digitorum. I have essentially done a local meridian treatment on the “Large Intestine” and “San Jiao” meridians. Muscles are included in the meridian system, and many points are potent in part due to their anatomical location.
Blood vessels are another facet of the meridian system. Returning to the Lung Meridian as an example, one of its acupuncture points, called Tai Yuan or "Great Abyss," is classified as the "Influential Point of the Pulse and Blood Vessels." It is no coincidence that this point happens to be found just beside the radial artery on the wrist, and that needling it affects the body's circulatory system.
Perhaps most interesting are the Bonghan Channels, named after Kim Bonghan of North Korea, who published papers describing them in the 1960s. Recently, A group of Korean researchers have rediscovered these threadlike microscopic anatomical structures[5], and found that they also correspond with the layout of acupuncture meridians. Bonghan Channels have been found inside of blood and lymphatic vessels and they also form networks that overlay internal organs. According to David Milbradt, L.Ac’s article[6] in Acupuncture Today,
Although [Bonghan’s] discoveries were confirmed by the Japanese researchers Fujiwara and Yu in 1967, his work was discounted by other scientists because he never revealed his formula for the staining dye that revealed these structures. Almost 40 years later, [his] discoveries have been confirmed by a variety of studies with rats, rabbits and pigs. Stereo-microscope photographs and images from transmission electron microscopy in the research papers show assemblies of tubular structures 30 to 100 μm wide (red blood cells are 6-8 μm in diameter).
Apparently these structures have remained undiscovered for so long because they are almost transparent and so thin that they are barely visible with low-magnification surgical microscopes. They are also easily confused with fibrin, which coagulates and obscures these structures [visually] when there is bleeding in dissected tissues. Now that they have been rediscovered, researchers are investigating their composition and function. The tubular structures that make up Bonghan Channels contain a flowing liquid that includes abundant hyaluronic acid, a substance that cushions and lubricates the joints, eyes, skin and even heart valves. Also visible in the photographs are small granules of DNA or microcells about 1-2 μm in diameter that contain chromosomal material highly reactive to stem-cell antibody stains. When these cells were isolated and then induced to differentiate, they grew into cells of all three germ layers. These may be our body's natural source of pluripotent adult stem cells, with the potential to develop into any cell in the body.
Bonghan Channels could account for acupuncture’s ability to stimulate the body to more rapidly heal tissues, but they remain only a piece of the whole that characterizes acupuncture’s immense and far-reaching therapeutic effects.
If we review the older concepts of waterways, we can see that the picture is much broader than a simple line of water running through land. Similarly, we need to conceptualize the meridian system as more than simple lines on the body. Like the longitudinal and latitudinal lines on a map, meridians make an excellent reference for acupuncture, massage, etc., and like the terrain those maps represent, meridians truly encompass a much fuller and richer depth of the human body's form and function.
[1] Langevin HM, and Yandow, JA. (2002), Relationship of acupuncture points and meridians to connective tissue planes. Anat. Rec., 269: 257–265. doi:10.1002/ar.10185
[2] Langevin HM, Churchill DL, Cipolla MJ. 2001a. Mechanical signaling through connective tissue: A mechanism for the therapeutic effect of acupuncture. FASEB J 15: 2275–2282.
[3] Langevin HM, Churchill DL, Wu J, Badger GJ, Yandow JA, Fox JR, Krag MH. 2002. Evidence of connective tissue involvement in acupuncture. FASEB J 16: 872–874.
[4] Langevin HM, Churchill DL, Fox JR, Badger GJ, Garra BS, Krag MH. 2001b. Biomechanical response to acupuncture needling in humans. J Appl Physiol 91: 2471–2478.
[5] Johng, Hyeon-Min et al. “Use of Magnetic Nanoparticles to Visualize Threadlike Structures Inside Lymphatic Vessels of Rats.” Evidence-based Complementary and Alternative Medicine 4.1 (2007): 77–82. PMC. Web. 23 Sept. 2016.
[6] Milbradt, David, L.Ac. "Bonghan Channels in Acupuncture." Acupuncture Today 10.4 (2009)