The Historical & Anatomical Evolution of the Sanjiao: Through the Chinese Classics to the Modern Era

By Cody McBeath

     Mired in controversy and debate, the Sanjiao’s anatomical mystery has pervaded the Chinese medicine landscape since the earliest writings of the Huangdi Neijing up till present day. Dubbed the ‘unique’, ‘unusual’, or ‘orphaned’ fu, the Sanjiao’s location, shape, and structure has confounded many Chinese medicine practitioners, mirrored in the conflicted streams of thought found throughout classical Chinese literature and subsequent commentaries that followed (1). Even today, the Sanjiao is a concept that is at the center of puzzled discussions of the modern era, leading to numerous assumptions pertaining to its Western anatomical and physiological equivalent. By contextually exploring the anatomical and physiological framework surrounding this ‘unique’ fu and its evolution through Chinese medical history, our understanding of the Sanjiao will be greatly enhanced.
    Specifically, this paper will assess the Sanjiao over the course of three distinct periods. The first historical era will highlight ideas pertaining to the Sanjiao as cited in the Huangdi Neijing Suwen compiled during the Warring States period and early Han dynasties. Next, analysis of the Sanjiao during the late Han dynasties will focus on writings found in the Lingshu, the Nanjing, and commentaries from famed Chinese scholar- practitioners. Lastly, hypotheses and correlations from modern Chinese medicine scholars and Western surgical doctors will be taken into account and evaluated in comparison to prior historical interpretations (5).
    The idea of systematic correspondence is ubiquitous throughout Chinese philosophy, with roots in thought, perception, and cultural attitudes toward phenomena. Chinese culture symbolically viewed the human organism, both anatomically and physiologically, as a mirror image of political and economic entities of the state. This system of correspondence conceptualized the Sanjiao as some sort of heating device within the human being (6). The birth of Chinese medical literature coincided with great technological advancements during the Han dynasty, specifically one of the most sophisticated and important economic functions of the time: ironworking and metallurgy. Hence, one of the reasons the Sanjiao is often referred to as the Triple Heater, Triple Burner, or Three Burning Spaces. In addition, during the late Han dynasty and last centuries BCE, inductive reasoning was the dominant force of cognitive thought (5). So, hypotheses on physiological function of the organism were surprisingly precise, while ideas on anatomical form were rather simple and rudimentary. Therefore, the Sanjiao was given a variety of functions, yet neglected in attempts to define its physical location. Also, due to the Sanjiao’s all- pervasive influence on the interior and lack of form, some scholar- physicians viewed it within a Taoist scope of perception, associating it with a kind of ‘formlessness’ (7). All in all, these ideas can be summarized by the often quoted line alluding to the Sanjiao as having “a name but no form” (3).
    From here, there is now a contextual basis that informs our discussion of the Sanjiao through the history of Chinese medical literature. Naturally, the Huangdi Neijing is the foundation for starting our analytical dissection of this unusual organ. Chapter 8 of Neijing Suwen states: “The Sanjiao is the officer who is in charge of drains and irrigation: it is the place from which water pathways emerge” (7). The Neijing Suwen symbolically designates the Sanjiao with a functional role as an official in the Imperial state. As we will see, over the span of about three hundred years, the Neijing Lingshu develops ideas surrounding the Sanjiao to include not only its functional aspects, but begins its designation as a tangible entity.
    After the writings of the Huangdi Neijing Suwen were compiled, the Nanjing, translated as Classic of Difficulties, was designed in a question and answer format with specific intentions of examining and clarifying contradictory theories and ideas found in the Neijing Suwen. This era of dominant cultural thought was highlighted by the works of the famed philosopher Wang Ch’ung, in addition to medical theorists such as Chang Chung- ching, Wang Shu-ho, and whoever was responsible for the works of the legendary surgeon, Hua T’uo (5). During this period, the Sanjiao had come to be viewed as a distinct entity, in large part because its lack of form was disturbing to many Chinese medical scholars. Thus, attempts were made to define the spatial location of its substrate based on the crude anatomical knowledge available at the time.
    The following excerpt from the Chapter 18 of the Lingshu emphasizes this point: “The upper jiao comes from the pylorus to the throat above, distributing in the chest and reaching the armpit, and follows the branches of the taiyin as it travels. It turns to reach yangming, ascends to the tongue, then descends to the leg yangming. The middle jiao is also together with the middle of the Stomach. It comes from the Stomach under the upper jiao. The lower jiao separates around the intestines, water comes out from the lower jiao and permeates the urinary Bladder” (2). From this description, we can infer that the Sanjiao encompasses three cavities located in the trunk of the body and encapsulates specific internal organs located in each jiao. Located above the diaphragm, the upper Burner includes the Heart and Lungs. Between the diaphragm to the umbilicus, the middle Burner includes the Spleen and Stomach. Lastly, below the umbilicus, the lower Burner includes the Liver, Kidney, and Bladder.
    Further, metaphorical descriptions of the energetic nature of the Sanjiao were created, suggesting that the Sanjiao was a key participant in the metabolic functioning of the organism, transmitting and assimilating energy through its conductive passageways (5). Another passage from Chapter 18 of the Lingshu describes this energetic, metabolic nature of the ‘three burning spaces’: “The upper Burner is like a mist, or fog; the middle Burner is like a maceration chamber, humidifier, pickling pot, or compost heap; the lower Burner is like a ditch or drainage canal” (1). Again, these ‘three burning spaces’ are correlated with specific regions of the trunk, with the upper, middle, and lower jiao corresponding to the physiological functions of the chest, abdominal, and pelvic cavities, respectively (2).
    While the Suwen documents the symbolic functions of the Sanjiao, and the Lingshu furthers its physiological functions as a tangible entity, it is not until the compilation of various commentaries in the Nanjing that we begin to see conflicted discussions pertaining to the Sanjiao's specific anatomical substrate. From the 25th Difficult Issue, Yang states: “The Triple Burner has a position but no physical appearance”. In contrast, from the 31st Difficult Issue, Ye Lin describes: “It is a fatty membrane emerging from a tie between the kidneys. The Triple Burner is associated with the residence of the minister fire. The nature of fire is to ascend from below”. Also, from the 31st Difficult Issue, Huang Weisan mentions: “The Triple Burner encloses all the long- term depots and short - term repositories externally. It is a fatty membrane covering the entire physical body from the inside”. Finally, the most emphatic of scholarly commentators, Xu Dachun declares in the 38th Difficult Issue: “How could one say that it has no physical appearance! It is spread out all around the upper and lower [parts of the body], enclosing [all the other] long- term depots and short- term repositories. Its form differs from that of the five short- term repositories, each of which has its distinct body. Hence, its appearance cannot be defined [in the same way]. But to say ‘it has no physical appearance’ - - that is impossible” (6). It’s evident from the following passages that the Sanjiao constitutes a “membrane” enclosing the “long- term depots” and “short- term repositories”, and according to some, covers the entire physical body from the inside.
    At this point, an interpretation of jiao may enhance our clarity of this fu. In the Cihai, the translation for jiao gives two entries: “1. special word for the Sanjiao; 2. muscles fail to fill the shell” (2). Therefore, we can imply that the Sanjiao represents the idea of an anatomical entity comprised of spaces that fail to fill the shell of the human organism. These spaces form large cavities not only in the trunk, but small spaces located throughout the extremities of the body. Looking back on a previous passage from Chapter 18 of the Lingshu, the Sanjiao follows the branches of the Taiyin channel of the Lung and Spleen and travels the Yangming channel of the Large Intestine and Stomach. Hence, this indicates that the Sanjiao's influence and location pervades the skin and flesh of the extremities as well. This is supported by Ding Jin’s reference to the treatise “Wu long jin ye bie lun” from the 25th Difficult Issue of the Nanjing: “The Triple Burner emits Qi to warm the muscles and the flesh and to fill the skin” (6). Also, the Sanjiao does not have a fixed, defined physical shape or size of its own, whereas the other fu are ‘repositories’ that can be measured, have their own shape, form, color, and have the ability to be filled and emptied. This implies that the Sanjiao does not occupy a concrete position of its own, but rather takes its form based on structures it encapsulates within the human frame. In Chinese medical theory, it is known that the Sanjiao is said to contain and regulate the physiology of the zang- fu organ network. The structural, three- dimensional network of the Sanjiao is not restricted to a particular area of the body, but rather mediates the physiology of the body trunk, the zang- fu organs, the muscles, the skin, and the spaces between these entities. By reviewing the classical texts, one can see that the all- pervasive network encompassed by the Sanjiao supports its physiological functions as a pathway for Qi, a pathway for fluids, a site for Qi transformation, and a passageway to distribute transformed materials and discharge turbid Qi (2).
    The last stage of our analysis will extend to the beginning of the twentieth century, examining the Sanjiao based on modern scientific thought and its association with concrete anatomical structures and physiological systems. This period is characterized by hypotheses and reductionist assumptions pertaining to its Western medical equivalent. Many of these scientific inferences analyze the Sanjiao through the lens of a scientific materialist. By aligning the Sanjiao with specific structures and systems of the Western medical establishment, the hypotheses fail to account for ancient cultural conceptions and Chinese medical theories. For example, the modern physicians, Bachmann and Schmitt believed that the Sanjiao can be identified with the endocrine system. However, this assumption lacks validity because pathology of the Sanjiao includes neuralgia and neuralgic affections. Thus, these symptoms cannot be attributed to dysfunction caused by the endocrine system (5). In addition, some modern acupuncture practitioners have likened the Sanjiao to the lymphatic system. While similarities between the Sanjiao and the lymphatic system include Wei Qi circulation/ immunity, Yuan Qi/ body fluid circulation, removal of Turbid Qi/ waste, and assistance in transforming of food and grain in the Spleen/ digestion via lacteals, the relationship doesn’t account for the vastness of the Sanjiao's connective network and distribution of small spaces throughout the extremities. However, hypotheses that relate the Sanjiao to the connective tissue/ fascial network and interstitial fluid spaces do seem to take into account the vast energetic conductivity and spatial distribution that permeates the human body (4). In Chinese medical theory, these smaller spaces are known as couli. In clause 1-2 of the Jinkui Yaolue Fanglun, author Zhang Zhongjing states: “Cou is a place of the Sanjiao where there is a passageway of circulation and convergence of yuan qi and zhen qi, filled by blood and qi; li is texture of skin and zangfu” (2). According to Qu Lifang and Mary Garvey in their article, The Location and Function of the Sanjiao, li historically meant “the markings in jade or the fibers in muscle; as a verb it meant to cut things according to their natural grain or divisions” (2). The interpretation of li as “cutting things according to their natural grain” bears striking resemblance to the description of Western surgeons cutting incisions along the fascial planes to reduce scarring (4).  Further, Donald Harper, a scholar who studied the Mawangdui medical manuscripts, interprets li as “network” or “network of vessels”, conveying the idea of li as a pattern or system. Taken together, couli can be interpreted as space and texture within a network or system. From an anatomical standpoint, the couli are correlated with the texture of the skin, muscles, zang- fu, and the interstitial spaces that exist between these physical forms. Therefore, the couli takes on the shape and size of the spaces they fill or the structures that they surround. Together, the couli form a matrix that spans upper and lower, interior and exterior. The spaces, textures, and interstices of the couli are emblematic of the Sanjiao’s membranous nature and passageways permeating the body.
    By reviewing and comparing the Sanjiao through classical Chinese medical literature with modern Western hypotheses as to its anatomical equivalent, the Sanjiao's evolution can be understood with enhanced clarity. From a formless ‘unique’ fu, to a membranous anatomical substrate composed of small spaces, to its relationship with the fascial network and interstitial spaces, the Sanjiao has been contextually framed based upon the period of the inquirer. For the curious scholar, practitioner, or layperson, returning to classical sources will continue to reveal the mysterious, enigmatic nature of the Sanjiao.
References
(1) Dharmananda, S. Triple Burner (Sanjiao) with reference to treatment of Sjögren's      Syndrome. http://www.itmonline.org/articles/triple_burner/triple_burner.htm.             Published October 2010. Accessed November 13, 2017.

(2) Garvey, M. & Lifang, Q. “The Location and Function of the Sanjiao". The Journal of             Chinese Medicine. 65 (2001) 26-32. Print.

(3) Grossman, G. The Medical Acupuncture Web Page. Cultural Reference for                 Increased Understanding of the San Jiao. https://med-vetacupuncture.org/                english/articles/sanjiao.html. Accessed November 13, 2017.

(4) Keown, D. The Spark in the Machine: How the Science of Acupuncture Explains the             Mysteries of Western Medicine. London: Singing Dragon; 2014.

(5) Porkert, M. The Theoretical Foundations of Chinese Medicine: Systems of                 Correspondence. Cambridge Mass.: MIT Press; 1985. pp. 158-162.

(6) Unschuld, P.U. & Bian, Q.: Nan-Ching the classic of difficult issues. Berkeley:                 University of California Press; 1986.
(7) Wang, J-Y. & Robertson, JD. Applied Channel Theory in Chinese Medicine: Wang             Ju-Yis Lectures on Channel Therapeutics. Seattle: Eastland Press; 2008.