What makes a meridian & a point?

Vivien Shaw

Member: Gwynedd

Meridians are often thought of as esoteric channels through the body that carry qi and have no visible physical substrate. However, in historical records from Han-era China, at the point where acupuncture was first developed (roughly 2,000 years ago) there is a record of a criminal being dissected as part of his punishment. The stated purpose of this dissection was to be able to, ‘trace the course of his blood vessels in order to learn where they began and ended. This knowledge could be used to understand disease.’ (Pan, Dubs & P’an Lo-Chi, The History of the Former Han Dynasty. Vol III)

The seminal text The Yellow Emperor’s Classic of Internal Medicine (Huángdì Nèijīng 黄帝 内經), a compendium of texts spanning nearly 400 years, describes acupuncture for the first time. It likewise describes using dissection to understand human anatomy and says that the descriptions of meridians are based upon this knowledge. My research is based on the assumption that these records are accurate. I have sought to understand how an anatomist at that time would understand what they see when looking at the body without the preconceived ideas that come from being taught what to expect.

Ancient Chinese texts are very terse, and the various available translations differ widely. I therefore started by translating the original texts as literally as possible, and then conducted many dissections of human cadavers using those texts as my guide. My aim was to follow the map of the body that they described.

I will talk here first about the translation of jing 經as ‘meridian’. The act of translation often involves additional interpretation to try to arrive at the best equivalent word. Multiple translations of jing have been suggested, including words like channel, conduit, etc. I discuss where the translation of ‘meridian’ comes from and the broader historical context in which it sits.

In the second part of this article I look at some specific acupoints, showing the underlying anatomy. Finally, I consider how an understanding of the anatomical structures underpinning meridians and points could be used to explain the clinical results that we see from needling them.

Historical & anatomical context for meridians

The word jing was translated as ‘meridian’ by a Frenchman called George Soulié de Morant who lived and worked for about 20 years in Shanghai as part of the French diplomatic corps, before returning to France in 1917. Fluent in Chinese, he became interested in acupuncture and was the first westerner to be trained as an acupuncturist.

China was ruled at the time by the last Qing emperor, and for Soulié de Morant to be allowed access to this system of medicine was a great honour. After returning to France, he wrote the first textbook of acupuncture in Europe. This book, L’Acuponcture Chinoise, is therefore a record of acupuncture as it was practised in China in the years preceding the Cultural Revolution.

In the chapter on meridians, Soulié de Morant explains his translation of jing as ‘meridian’ by saying: ‘the meridians (jing) are the longitudinal paths… the term jing was used in astronomy for the lines of north-south longitude. It is still used in the countryside for the northsouth paths of a field.’ This indicates that, from the beginnings of acupuncture,

analogies were being drawn between the microcosm of the human body and the macrocosm of the world around it.

The creation of maps based on grids like the one pictured here was an invention of the Han dynasty. These maps were of huge significance as they enabled better governance and use of the land, particularly for the purpose of agriculture and food production. The emperor ruled through the Mandate of Heaven, with droughts, famines and other natural disasters seen as bad omens that undermined that mandate. Managing land and water through good irrigation practices was therefore key not only to effective food production but also to maintaining a stable empire.

Grid-based maps were invented by Zhang Heng 張衡 (78-139 CE), who was the director of the Imperial Bureau of Astronomy and Calendrics. To create lines of longitude, you need two pieces of information. The first is to be able to see the North star, and the second is to accurately know the time. The innovation of inserting a grid system over a map of the terrain therefore relied on Zhang Heng’s astronomical abilities, and the existence of accurate clepsydra (water clocks).

The dissection record talked about the significance of finding the end points of the blood vessels

The value placed on the developing medical system can be seen through the connections that were being made through the use of the same word in the descriptions of the body and the maps. Describing the system of meridians in the body in this way also links the language of the body to the language of landscapes and the natural world, underlining the fact that the same paradigms for understanding the universe could be applied to both. These grid maps continued to be used throughout the ensuing centuries and, although none of Zhang Heng’s own maps have survived, the map from circa 1555 you see below is created using the same system.

When Han-dynasty physicians wanted to understand the human body, their primary interest was in the flow of blood, which irrigates and nourishes the body, just as water irrigates and nourishes the land. When examining a body, what we know as arteries, veins and nerves tend to run together as neurovascular bundles. The concept of a neurovascular bundle, however, is a modern one. If you are looking at a body without any prior knowledge about what it contains, what you see is three types of structure that tend to run together in longitudinal patterns. There are vessels full of blood (veins), hollow tubes (arteries) and structures that are dense and fatty (nerves).

As has already been shown in the dissection record, the Chinese were well aware of the significance of blood to health. They knew that that if you lose blood, you become weak. If you lose a lot of blood, you die. However, when looking at a cadaver, the body is still full of blood – which presents a conundrum. If the blood is still there, yet the individual is dead, then it logically follows that there must be another animating force involved in life.

The function(s) of the hollow and dense tubes that are visible running alongside the blood are unknown. However, they do run together with the blood, so it would be reasonable to assume that these hollow and dense tubes are also significant. In making their anatomical atlases, the Handynasty anatomists therefore created detailed maps not just of the main pathways through the body followed by the neurovascular bundles (the meridians), but also of the places where these structures changed in some way. This change could be where a bundle split apart, where blood vessels branched or came together, or where the blood vessels ended. The beginning and end points of the vessels had already been flagged as a particular point of interest, and one of the specific pieces of information that dissection of the criminal was intended to reveal. All of these internal landmarks were marked and named, and later became what we now know as acupuncture points.

View of the vessels of the plantar and dorsal surfaces of the foot

How meridians gave rise to points

The Han dynasty is famous for its scientific discoveries. Once physicians had observed and named the anatomy of the body – meridians and points – the next step in the scientific method would be to create hypotheses about the significance of the structures they had identified as being of interest, and test them.

As already mentioned, the control and management of water flow through the landscape was of huge significance at the time, and an understanding of how to manage fluid flow was very highly developed. Water supplies could be managed using locks, sluice gates, canals, wells and other engineered structures. (Solomon, Water: The Epic struggle for Wealth, Power, and Civilization

Within the Yellow Emperor’s Classic there are many analogies drawn between flow in the body and water flow across the land, for instance the five ‘command (shu 輸) points’, found on each meridian between the fingers and the elbow or toes and knee, which are called well, spring, stream, river and sea. These shu points are some of the earliest ones named in the early acupuncture literature. What they all

have in common are that they are found in areas of the body where the insertion of a needle has the potential to interact directly with the underlying structures because they are close to the surface. By comparison there are relatively few points in the big muscles of the thigh and the upper arm.

Above you can see a dissection of a foot in two views. The image of the underside (sole or plantar surface) of the foot has been made into an illustration, while the image of the top (dorsum) of the foot is just a photograph. The posterior and anterior tibial arteries are labelled in each case. The posterior tibial artery runs along the plantar surface of the foot, and the anterior tibial artery runs over the dorsum of the foot. The two arteries join to form an anastomosis between the first and second metatarsals, rather like a loop. The points found over this significant anatomical landmark are LIV 3 tai chong on the dorsum of the foot, and KID 1 yong quan on the sole (also labelled).

As mentioned above, the dissection record talked about the significance of finding the end points of the blood vessels. In many cases the vessels form what are known as terminal arteries, that is they become smaller and smaller until they come to an end at the extremities and on the head. The anatomical structure shown above by contrast, this loop where the two major vessels travelling along the front and back surfaces of the leg meet, has a remarkably different character. The same anatomical loop is also found in the hand, at LI 4 he gu on the dorsum, and P 9 zhong chong on the palm. Where the anterior tibial artery in the leg goes over the dorsum of the foot to LIV 3, the radial artery in the arm passes around the back of the wrist onto the dorsum of the hand before piercing through to the palm in between the first and second metacarpals. The ulnar artery in this instance is the pair or homologous structure of the posterior tibial artery.

Having found this unique configuration of major blood vessels in the limbs, it is logical to believe that they might have some equally unique properties, and that their similarity could make them function well together. Controlling or managing the flow of fluid at the end point of the loop could have the potential to enable an acupuncturist to bring balance to the two long vessels that connect at that point. This could theoretically then achieve a global effect through controlling the flow in the vessels through using these specific places (LIV 3 and LI 4). Clinical experience of needling these points absolutely substantiates this theory, and what is now known as the Four Gates treatment is one of the most frequently used methods to reduce stress, that is harmonise flow of qi and blood throughout the body.

In conclusion

As this example has shown, understanding the anatomical basis and historical context of meridians and points can enhance our understanding of what we do in clinic. The physiological mechanisms for how we think this works are culturally contextual. Han-era science was predicated on an understanding of five element theory. Modern scientific understandings of physiology are very different, but the anatomy on which our understanding of the body relies is unchanged. As acupuncturists and patients, we may have our own theories or preferences for explaining the physiology of our treatments, but what this research shows is that the original development of acupuncture was firmly rooted in the science of the time.