What are acupuncture channels? (And the organs that some of them are named after?)
When you come in for an acupuncture treatment with us, one of the things you might want to know is what we can tell you about a symptom you’re experiencing, and one of the things we can tell you is which acupuncture channel(s) that symptom affects. For example, if you have sciatica—often a sort of shooting electrical-like sensation that follows the sciatic nerve from the buttocks down the back of the thigh—the affected acupuncture channels are the Bladder and Gallbladder channels.
It is appropriate that the organs of Chinese medicine are capitalized like this, not only to distinguish them from their counterparts in conventional medicine but because the particular way in which they are different is that they have broader spheres of influence. While there is no thyroid gland among these organs, for example, this doesn't mean there is no concept of one. Some functions of the thyroid are in the sphere of influence of the Lung.
Now that you have a better idea of what the Bladder and Gallbladder are (or are not), it's time to get up to speed on their channels.
Sciatica actually occurs on a particular part of these channels called an external pathway. An external pathway is the part of an acupuncture channel where your acupuncturist does acupuncture on you. It is essentially a line connecting a channel’s acupuncture points, each of which have specific functions related to the overarching functions of that channel. Acupuncture points form tiny depressions on the body's surface—the Chinese character that is translated as "point" means "cave" or "hole." Those that are part of acupuncture channels have fixed locations that acupuncture students learn. Traveling from the inner corner of the eyes down the back side of the body to the outside of the pinky toes, the Bladder channel's external pathway has 67 acupuncture points—the most of any channel (to those acupuncture students' chagrin). The Gallbladder channel's external pathway, on the other hand, has "just" 44 acupuncture points and travels from the outer corner of the eyes down the sides of the body to the outside of the neighboring toes.
Where are the Bladder and Gallbladder in all of this, you might ask? Acupuncture channels also have internal pathways that connect their external pathways to affiliated organs. For the Bladder and Gallbladder channels, these include the organs they are named after (fancy that), as well as the Kidney and Liver, respectively. Thus, an acupuncture needle that barely penetrates the body's exterior can have effects deeper within its interior.
Gaining knowledge of the acupuncture channels'—and their acupuncture points’—locations and functions likely involved a centuries-long process of experimenting with treating different areas on the body’s surface, first with massage and later with acupuncture; observing the effects; putting these observations to the test; and summarizing the findings: basically, an early version of the scientific method.1 But the only possible way to explain how ancient Chinese texts contain accurate representations of the organs lying far beneath the body’s surface2 is that they had seen them. While it is often assumed, because the history of the study of conventional anatomy tends to take a Eurocentric viewpoint, that the ancient Chinese did not perform dissections, as a matter of fact there was an exception to the taboo on dissection under Confucian law that allowed them to peer inside the bodies of executed criminals3 long before dissection became philosophically permissible in Western Europe.4
Despite all of this, there is an ongoing quest to see what acupuncturist Richard Blackwell describes as “the anatomy of influences and interconnections”1(pvii) in the flesh—to figure out which of the many “channels” of conventional anatomy the acupuncture channels correspond to.
For example, it has been proposed that acupuncture channels “are the vascular, nervous[,] and conductive pathways of the human organism,”2(p114) or blood vessels, nerves, and muscles, respectively, with acupuncture points being foramina (openings) over these structures. According to a slightly more detailed hypothesis, the acupuncture channels starting or ending on the hands “describe single continuous structures like veins or arteries,” while those starting or ending on the feet (like the Bladder and Gallbladder channels), which are much longer, “are composed of a series of different structures, some neurovascular [pertaining to nerves and blood vessels] and some muscular."3(p1207)
However, there are plenty of areas along acupuncture channels that are explicitly not colocated with a nerve, artery, vein, or muscle, but rather serve as the thread knitting the structures in these areas together lengthwise from their sides as opposed to their ends; because these areas are arranged vertically relative to one another, the channels themselves still run in this direction. The Lung channel, for example, which ends on the hands, follows the lateral (thumb-side) border of the biceps brachii muscle in the arm and the radial artery at the wrist; its acupuncture points in these areas are located between the biceps brachii muscle and the shaft of the humerus bone, and the radial artery and the abductor pollicis longus tendon, respectively.5
What sort of structure is the "thread" in instances like this, then? And could it be the same as the one in those instances in which your acupuncturist placing a needle at a certain point on an acupuncture channel must take care not to stick it into your nerve, artery, or vein?
There is in fact a justification for the acupuncture channels that start or end on the feet being "a series of different structures," as these structures "have fascial connections with each other...to form diverse yet continuous pathways through the body."3(p1207) Fascia resembles a spiderweb, which is spun from silk—the meaning of a component of the ancient Chinese character for “acupuncture channel.” It surrounds blood vessels, nerves, muscles, bones, and organs6—the same structures that appear on or adjacent to acupuncture channels—linking these structures along connective tissue planes. These planes, which permeate the entire body8—like acupuncture channels—are collectively known as the connective tissue network.7 Because the connective tissue they are made of (fascia is a type of this aptly named tissue) is responsive to mechanical stimuli, these planes can transmit the mechanical signal produced by the insertion of an acupuncture needle through the structures they connect: “Acupuncture needle insertion…may cause lasting modification of the extracellular matrix surrounding the needle, which may in turn influence the various cell populations sharing this connective tissue matrix,”7(p260) such as fibroblasts, sensory afferent nerves, and immune and vascular cells.
It is possible that the system of acupuncture channels is a representation of the connective tissue network, with acupuncture channels representing connective tissue planes.7 Fascial connections have been found along acupuncture channels that start or end on the hands as well, which "appear to generally follow connective tissue planes separating muscles or within muscles [emphasis added]."7(p263) Additionally, acupuncture points are predominantly located at sites of thick connective tissue,9 where nerve endings and other powerful mediators of activity within the body abound9 and where acupuncture needle insertion can result in a greater mechanical stimulus,7 potentially making biological reactions there more intense.7-8
Regardless, the acupuncture channels can still be seen through other means, albeit indirectly. For example, infrared imaging has revealed thermal pathways that align closely with acupuncture channels when acupuncture points are exposed to heat using a Chinese therapy called moxibustion or moxa,10 while fluorescent dye (fluorescein sodium) injected into an acupuncture channel's acupuncture points has been shown to migrate in patterns consistent with the distribution of that channel and distinct from that of arteries and veins in the same region.11
If you’ve had acupuncture before, you might have even experienced a common phenomenon we call “phantom needle,” causing you to feel like there is a needle where there isn’t one—although chances are that there is one somewhere along the same acupuncture channel. In terms of discerning whether or not something exists, seeing might be believing, but nothing compares to feeling.
References Cited
Maciocia G. The Channels of Acupuncture: Clinical Use of the Secondary Channels and Eight Extraordinary Vessels. London, England: Churchill Livingstone; 2006.
Schnorrenberger CC. Anatomical roots of acupuncture and Chinese medicine. Schweiz Z Ganzheitsmed. 2013;25:110-118. doi: 10.1159/000349905.
Shaw V, Diogo R, Winder IC. Hiding in plain sight: Ancient Chinese anatomy. Anat Rec. 2022;305:1201-1214. doi: 10.1002/ar.24503.
Drossman DA. Functional gastrointestinal disorders: History, pathophysiology, clinical features, and Rome IV. Gastroenterology. 2016;150(6):1262-1279. doi: 10.1053/j.gastro.2016.02.032.e2.
Deadman P, Al-Khafaji M, Baker K. A Manual of Acupuncture. East Sussex, England: Journal of Chinese Medicine Publications; 1998.
Gatt A, Agarwal S, Zito PM. Anatomy, fascia layers. StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing; 2023. Available from https://www.ncbi.nlm.nih.gov/books/NBK526038/ (accessed July 2024).
Langevin HM, Yandow JA. Relationship of acupuncture points and meridians to connective tissue planes. Anat Rec. 2002;269(6):257-265. doi: 10.1002/ar.10185.
Bai Y, Wang J, Wu JP, et al. Review of evidence suggesting that the fascia network could be the anatomical basis for acupoints and meridians in the human body. J Evid Based Complementary Altern Med. 2011:1-6. doi: 10.1155/2011/260510.
Wang J, Dong WR, Wang CL, et al. From meridians and acupoints to self-supervision and control system: A hypothesis of the 10th functional system based on anatomical studies of digitized virtual human [in Chinese]. Nan Fang Yi Ke Da Xue Xue Bao. 2007;27(5):573-579. https://pubmed.ncbi.nlm.nih.gov/17545059 (accessed July 2024).
Schlebusch KP, Maric-Oehler W, Popp FA. Biophotonics in the infrared spectral range reveal acupuncture meridian structure of the body. J Altern Complement Med. 2005;11(1):171-173. doi: 10.1089/acm.2005.11.171.
Li T, Tang BQ, Zhang WB, Zhao M, Hu Q, Ahn A. In vivo visualization of the pericardium meridian with fluorescent dyes. Evid Based Complement Alternat Med. 2021:5581227-5581237. doi: 10.1155/2021/5581227.