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Table of Contents
RESEARCH ARTICLE
Year : 2018  |  Volume : 1  |  Issue : 2  |  Page : 84-87

Structure and distribution of the San Jiao and Cou Li – Recognized interstitium in human tissues


School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China

Date of Web Publication9-Oct-2018

Correspondence Address:
Prof. Lifang Qu
School of Basic Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 201203
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/CMAC.CMAC_23_18

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  Abstract 


Since the Yellow Emperor's Inner Canon (c. 200 bce), Traditional Chinese Medicine (TCM) has held that the san jiao system is the largest anatomical structure in the human body, and that it consists of a network comprising the large cavities in the body trunk and the small interstitial spaces between the tissues and cells throughout the body. More than 2000 years later, and according to recent scientific reports in America, this network of structures has been recognized by modern medicine. The two theories, TCM's san jiao and its system of spaces(腠còu), and the recent scientific discovery of an interstitial network in the human body, are quite similar in structure, distribution and function.

Keywords: Cavity, Cou li (腠理), interstitial, San jiao (三焦), TCM


How to cite this article:
Qu L. Structure and distribution of the San Jiao and Cou Li – Recognized interstitium in human tissues. Chin Med Cult 2018;1:84-7

How to cite this URL:
Qu L. Structure and distribution of the San Jiao and Cou Li – Recognized interstitium in human tissues. Chin Med Cult [serial online] 2018 [cited 2021 Jan 18];1:84-7. Available from: https://www.cmaconweb.org/text.asp?2018/1/2/84/242577






  Introduction Top


Recently, scientific reports[1] have been published on the structure and distribution of an unrecognized interstitium in the human body. The content is highly related to the structure and distribution of the San Jiao (三焦 sān jiāo) and Cou Li (腠理 còu lǐ) in Traditional Chinese Medicine (TCM), especially, cou-interstitial spaces (腠 còu) between the cells and tissues. It is time for TCM practitioners to recognize the partition and composition of the San Jiao-Cou Li system and their four main functions and features of the waterways (气道 qì dào), the pathway of qi (水道 shuǐ dào), the site of qi transformations (气化场所 qì huà chǎng suǒ), and the transmission of transformed substances/metabolin (转输化物 zhuǎn shū huà wù).

It is well known that the San Jiao is the largest, isolated, and most unique fu in TCM, and is translated as “triple burner,” “triple energizer,” “the three warmer,” and “triple jiao” in English. Chapter 8 in the Elementary Questions described San Jiao as “holds the office of the sluices, and manifests as the waterways.”

Throughout history, there have been many debates about the San Jiao. Here, we discuss this unique fu system as presented in TCM's early classics. From the Ling Shu (灵枢 Divine Pivot), Chapter 18:

“The upper jiao starts above the upper opening of the stomach, and flows upward along the throat. It penetrates through the diaphragm, spreads through the chest, runs to armpit and descends along the (lung channel) taiyin to the (large intestine channel) yangming.… The middle jiao also starts from the stomach. It is underneath the upper jiao.… The lower jiao emerges from the ileum, and infuses into the bladder, …food waste is transmitted to the large intestine. …I have heard that the upper jiao is like a mist, the middle jiao is like foam and the lower jiao is like a drainage ditch [Figure 1].”
Figure 1: San Jiao

Click here to view


And from the Jīn Guì Yào Lüè (金匱要略 Essential Prescriptions of the Golden Babinet) as:

“The interstices (腠 còu – the interstitial and intercellular spaces) are the place of the San Jiao where initiating (元气 yuán qì) and true (真气 zhēn qì) circulate and converge; they are filled and suffused with the blood (nutrients) and qi (clear qi, oxygen). The li (理 ) are the textures of the skin and viscera.”

From the above, we know clearly that the San Jiao system consists of two parts of cavities in trunk and interstices between the tissues and cells from skin to zang fu,[2] which make us confirm San Jiao theory in terms of its location and features and its partitions and functions.


  The Partition and Composition of San Jiao Top


Three big cavities in the trunk

Conventionally, San Jiao consists of three partitioned regions: the upper jiao, middle jiao, and lower jiao [Figure 1]. The partitioning of San Jiao is given in The Divine Pivot, Chapter 18: “The upper jiao starts above the upper opening of the stomach, and flows upward along the throat. It penetrates through the diaphragm, spreads through the chest, runs to armpit… up to tongue.” The middle jiao also starts from the stomach. It is underneath the upper jiao.…. The lower jiao emerges from the ileum, and infuses into the bladder.”

Every organ and tissue have their own name and function. What remained, except they contain organs and tissues, are related to the San Jiao. For example, when the heart and lung are removed from the chest, a thoracic cavity remains, which clearly shows that the upper jiao, similar to middle and lower jiao, mainly refers to the thoracic, as well as abdominal and pelvic cavities.

Within the three large cavities in the body trunk, the San Jiao's qi-functions are carried out by the viscera located within them. However, the thoracic, abdominal, and pelvic cavities are only a part of the San Jiao system, and the Divine Pivot's description of the upper Jiao clearly includes all of the body above the diaphragm – the chest, heart, lungs, head, arms, and so on.

The upper jiao's qi-functions are to disperse and distribute transformed pure food essence, the clear body fluids, qi and blood, throughout the body. Thus, the upper jiao is described as a “mist” (雾 ). Together, the qi-functions of the heart and lung achieve the upper jiao's dispersing and distribution activities, and because they are situated in the thoracic cavity, the chest region tends to represent the upper jiao. But in fact, not only the large chest cavity but also all the small interstitial gaps and intercellular spaces above the diaphragm belong to the upper jiao.

The middle jiao is the area under the diaphragm and above the navel, and in TCM, this region contains the spleen and stomach. When the spleen and stomach are removed, there mainly remains abdominal cavity. It is the function of the middle jiao, the spleen and stomach, to ferment, decompose, and transform our dietary intake into nutrient substances, and so the middle jiao is said to be like a “retting” (沤 ōu). Like the upper jiao, the middle jiao is the abdominal cavity containing not only the spleen and stomach but also all the abdominal region cavities.

The lower jiao is the area below the navel. In TCM, it contains the kidney and liver (functionally), urinary bladder, large intestine, small intestine, uterus, legs, and feet. Because the lower jiao discharges waste from the body, it is described as the “drainage” (渎 ). The large pelvic cavity in particular, including all the small spaces throughout the lower body, is regarded as the lower jiao. Therefore, the functional states of san jiao are described as that the upper jiao is like a mist, the middle jiao is like foam, and the lower jiao is like a drainage ditch.

Interstitium between the tissues and cells

The Jīn Guì Yào Lüè (金匱要略), written by Zhongjing Zhang [Figure 2] (pp. 152–219), explains this aspect of the San Jiao system in more detail. In Chapter 1, Zhang Zhongjing describes this other indispensable structure of the San Jiao system: “The interstices are the place of the san jiao where initiating and true (真气 zhēn qì) circulate and converge; they are filled and suffused with the blood (nutrients) and qi (clear qi, oxygen). The li (理 ) are the textures of the skin and viscera.”
Figure 2: Zhongjing Zhang (张仲景)

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The spaces and textures (腠理 còu lǐ) are often mentioned together and individually in the Inner Canon. It is well known that the textures are arranged by the different cells and tissues to form the viscera, where there must be spaces, gaps, and interstices. It is Zhang Zhongjing who concluded that the San Jiao system consists of two parts of the large cavities in trunk that are connected to all the small spaces between the cells, tissues, and viscera throughout the rest of the body.

Kun Wu (吳崑 Wú kūn 1552–1620) explained that the “cou” (腠 còu) are the sweat pores, and li (理 ) are the textures of the muscles. According to Jingyue Zhang (张景岳 Zhāng Jǐngyuè, 1563–1640), “The cou are the body spaces, the place where the blood and qi are coming and going; they are the road where the San Jiao circulates and the initiating qi and true qi converge. The li are the orderly textures from the skin to the viscera.”

It is very clear that the li-textures are the textures and striations of body tissues and structures from the viscera internally right out to the skin and fine body hair externally. Every texture is formed by the orderly arrangement of cells and tissues according to their place and function. They are part of the San Jiao's network of cavities and spaces because they define and characterize the cou-interstitial spaces between the cells and tissues. Where there are certain textures of cells and tissues, there must be a space between them. This is why the inner canon often mentions the 腠理 (còu lǐ) together. Thus, the Golden Cabinet describes clearly that cou-interstitial spaces (腠 còu) between the cells and tissues affiliate San Jiao.

While there have been many viewpoints about the San Jiao over the years, opinions on its physiological functions are coincident. For students of TCM today, it is important to understand, not only the San Jiao's physiological functions, but the actual partitioning structures and locations of the San Jiao that carry out those functions. In TCM's ancient classics, these features are very clear: the location and structure of the San Jiao system consists of the three partitioned regions that are the large cavities in the body trunk, and all the small interstitial, small gaps, and spaces between the cells, tissues, and viscera throughout those regions and the whole body.


  The Functions of San Jiao (Cou Li) Top


The San Jiao has four main functions and features:[3] it is the waterways, the pathway of qi, the site of qi transformations, and the transmission of transformed substances/metabolin (转输化物 zhuǎn shū huà wù).

The qi pathway (气道 qì dào)

In the Nan Jing (难经 Classic of Difficult Issues 100 ce), Issue 31 says that, “The san jiao is the end and the start of (the course of) the qi.” In TCM, the San Jiao's qi pathway is the place where the three qi converge. Different interpretations of the “three qi” emphasize their different activities; however, the three qi refer mainly to the source qi (原气 yuán qì), initiating qi, and the defense qi (卫气 wèi qì).

The source qi, also called the “original qi, the primary qi, arises from the life gate (命门 mìng mén) and pours into the viscera via San Jiao's network of cavities and spaces that are distributed throughout the body. The Classic Difficulties, Issue 38 says, “The san jiao is another route of the source qi, and in charge of all kinds of qi.” It means that all kinds of qi are transformed by source qi. The initiating qi also derives from life gate. It is the first power to instigating life process and main energy to keep life activities. One part of the defense qi derives from the life gate in the low jiao. The Divine Pivot, Chapter 18 says: “Defense comes from the low jiao.” Defense qi is distributed to all the interstitial spaces and textures between the cells and tissues, the muscles and viscera, in order to protect them from evils. (For more details, see Section 1 in Chapter 2. and the qi, blood, and body fluids in Chapter 4.)

In this way, the San Jiao's qi passageway function stimulates visceral physiology and maintains orderly and harmonious life processes. The three kinds of qi together fill the spaces and cavities of the San Jiao to maintain normal visceral functions and maintain the conditions for good health. The San Jiao's qi pathway must be kept clear and open to assist orderly qi movement, the ascending–descending, and floating–sinking qi dynamic that is essential for orderly qi activities and life processes.

The waterways (水道 shuǐdào)

In TCM theory, San Jiao is regarded as the place where the fluids pass through. The Elementary Questions, Chapter 8 says: “The san jiao is the officer who is in charge of drains and irrigation; it is the place from which the water pathways emerge.” This means that the San Jiao's system of cavities and spaces is an important site for fluid metabolism because it enables the orderly ascending, descending, moving inward, and moving outward (discharge) of fluids.

The retention of excessive water in the spaces between the cells and tissues (edema) and the retention of fluid in the abdominal cavity (ascites) are well-known disorders of fluid metabolism. Both clearly remind us that the spaces between the cells and tissues and the body cavities are part of the San Jiao's structure that serves as the place for the movement and transformation of fluids – the waterways. The main functions of the San Jiao waterways are actually carried out by three of the zang, the spleen, lung, and kidney, and two of the fu, the San Jiao itself, and the urinary bladder.

The site of qi-transformation (气化场所 qì huà chǎng suǒ)

The “site of the qi-transformation” [Figure 3] refers mainly to the physiological processes that take place in the San Jiao's network of spaces and textures. The theory is taken from the Golden Cabinet, Chapter 1.
Figure 3: The site of qi-transformation

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In TCM, qi is like a kind of very small, very fine substance, and generally speaking, we divide the body's transformations (化 huà means change and transformation) into two kinds of processes, one governed by the spleen and the other by the kidney. The former is called transportation and transformation (运化 yùn huà). These are first-stage digestion and absorption metabolic processes. The latter is called qi-transformation (气化 qì huà), second-stage and more refined set of transformations, which are similar to the modern medicine's catabolic and anabolic processes.

The kidney's qi hua functions are the transformations of these very fine qi-substances that take place in microscopic tissue structures and cells. For all the cells and tissues to carry out their work correctly, they need the stimulus and drive of the initiating qi, and the real-life information of the true qi (真气 zhēn qì), which the San Jiao supplies from the life gate.

In addition, the nutrient qi (营气 yíng qì) from the spleen, clear qi (清气 qīng qì, or oxygen) from the lung, and defense qi from the San Jiao's upper, middle, and lower regions protect the viscera, tissues, and cells from disturbance and disruption by various evils.

Transmitting transformed substances (转输化物 zhuǎn shū huà wù)

Another important function of the San Jiao system is its transmission of the substances transformed by the cells, tissues, and viscera and absorbed into the spaces between them. It is called transmitting transformed substances (转输化物 zhuǎn shū huà wù) in the Yellow Emperor's Inner Canon, Chapter 11: “The stomach, large intestine, small intestine, san jiao and bladder … receive turbid qi from the five zang. They are called the fu of transmission and transformation.” The San Jiao's network of spaces is an especially important site for metabolic activities at the cellular level. All the metabolic products from all kinds of cells are carried away by the body fluids surrounding them and the San Jiao's network of interstitial and intercellular spaces, and are finally discharged with the urine and sweat.

In short, it is very important to understand San Jiao's partitioned structure and functions. The partitioning of San Jiao defines its network of large cavities in the body trunk, and all the smaller interstitial, gaps, crevices, and spaces that exist between the viscera, tissues, and cells that extend out to the limbs and body surface. Collectively, the body's network of cavities, gaps, crevices, interstitial spaces are the San Jiao fu, and this explains the uniqueness of the sixth fu system. This is why the San Jiao is the largest of the viscera, how it contains all the other viscera, and why the San Jiao's functions cannot be achieved without the zang fu organs enclosed within it.

The San Jiao is also said to be isolated and unique among the fu because, unlike other viscera, it has no yin (internal–external) partner. However, it is governed by the kidney, and the kidney governs water; it corresponds to the urinary bladder internally, and to the cou li-spaces and textures of the skin cells and soft body hair externally. Chapter 47 in the Divine Pivot says, “The kidney responds to the san jiao and the bladder, which respond to the cou li and soft hair.”

Functionally, the San Jiao system of cavities and interstitial spaces is an important site for metabolic functions. It serves as the qi pathway and the waterways, the place for their convergence, and serves as the place for qi transformations and for the transmission of transformed substances from cell metabolism. The San Jiao's network is comprised of all kinds of cavities and spaces that must be kept clear of obstructions so that qi influences and substances, water, and body fluids can pass through smoothly. Unobstructed movement facilitates physiology and ensures that the substances produced by tissues and cells are transported and cleaned away efficiently. Uremia is a disease example that illustrates the importance of these movements and transformations.

The San Jiao is also a model for syndrome differentiation for TCM's School of Warm Diseases and its analysis of external pathogens. To diagnose all kinds of warm diseases, this method identifies signs and symptom clusters according to whether they affect the upper, middle, or lower jiao. The principles of treatment for the San Jiao model of warm diseases and patterns are described as mist like for the upper jiao, balanced and harmonizing for the middle jiao, and downbearing for the lower jiao.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Benias PC, Wells RG, Sackey-Aboagye B, Klavan H, Reidy J, Buonocore D, et al. Structure and distribution of an unrecognized interstitium in human tissues. Sci Rep 2018;8:4947.  Back to cited text no. 1
    
2.
Lifang Q, Garvey M. The location and function of the Sanjiao. J Chin Med Engl 2001;65:26-32.  Back to cited text no. 2
    
3.
Lifang Q, Garvey M. Traditional Chinese Medicine Basic Theory: Shanghai World Publishing Corporation; 2018.  Back to cited text no. 3
    


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