San Jiao, a Fu-viscus, includes all internal organs in the chest and abdomen as a functional system (sub-intangible viscus). We must try to get used to this Oriental thinking. While this is basic to TCM holistic philosophy, it is difficult to understand by the thinking of CWM. However, in relation to San Jiao, the term “viscus” has a special meaning, unlike the definition of an organ as used in modern anatomy. There is most consideration of holistic or “system” functions, but not the structure details. The water metabolism is more complicated and deals with all the organs including Five-Zang and Six-Fu all over in the big cavity, which is a function system.TCM utilized their advantage of visualization to find this system: The Miraculous pivot says, “The Upper Jiao (chest) looks like a cloud of mist; the Mid Jiao (between diaphragm and navel), fermented food mixing with water; the low Jiao (abdomen), an active network of water” TCM nominates this function system of water metabolism and Qi transformation as the San Jiao viscus. This is the ancient Oriental philosophy and wisdom that solved the complicated problem (tangible with intangible). It is important to understand that the different thoughts of the East and the West then overcome the difficulty of learning TCM. While it is a functional system like the other five Fu-viscera, San Jiao also consists of all the internal organs (some of which are Fu-viscera themselves) in the chest and abdomen as a whole; although it has its own distinct functions, there is no tangible individual organ (not necessarily related to its component). It is a further, rather abstract concept defining San Jiao. While it acts on tangible substances and bodily processes (physiological and pathological phenomena and functions), as well as influences intangible matter, energy, and messages, such as Qi, thus taking it out of the scope of CWM. In short, it is a visceral system that emphasizes holistic function and not anatomical structure. San Jiao is concerned with the complete process of Qi transformation, the ingestion, digestion, transmission, and excretion of food and water. It is important to allow a paradigm shift from Western science and CWM to acknowledge this viscus, which processes not only food and water but also the invisible energy and information belonging to the intangible body. Thus, if we acknowledge intangible aspects in the makeup of the human species, it should be a small shift to assimilate the San Jiao concept. It is a good example to help people understand the uniqueness of TCM theory, which contains some “tacit knowledge”and “system science”principles.
The San Jiao Meridian may be easier to understand than San Jiao viscera; it connects with, and is externally–internally related to, that of the Pericardium one. San Jiao passes on primordial-Qi and transmits body fluid; The Basic Questions says, “The San Jiao is the official in charge of irrigation and it regulates the water passage” . TCM conceives of San Jiao as a great Fu-viscus in the thoracic and abdominal cavities, and it is the largest of the viscera.
The functions of San Jiao
(1) San Jiao regulates the general circulation channel of primordial Qi and body fluid
The primordial-Qi, generated from congenital and acquired Essence, originates in Shen, and is the origin of vital activity. San Jiao is an “avenue” for the primordial-Qi. It also regulates the various types of Qi within the body, and controls all Qi transformations in the body.
The body’s water metabolism is accomplished by the coordinated action of several viscera: Fei (
Lung system) Pi (
, Spleen system), Large and Small Intestines, Shen (
, Kidney system), and Bladder. However, to guarantee normal circulation and to metabolize water, the fluid must go through San Jiao. San Jiao’s Qi transformation is coordinated with its water metabolism since fluid transmission depends on the power of Qi motion. As San Jiao’s passing of primordial-Qi and transmission of body fluid are two related aspects of one function, San Jiao serves as the common passageway of Qi and body fluid.
(2) The San Jiao is a three-division grouping for certain viscera
San Jiao is the collective term for the Upper Jiao, Middle Jiao, and Lower Jiao. The Miraculous Pivot says, “The Upper Jiao is like a mist, the Middle Jiao like a maceration chamber, the Lower Jiao like a sewer”
| (a) | The Upper Jiao is located in the thoracic area above the diaphragm, and includes Xin ( Heart system) and Fei. It works like an atomizer spraying nurturing fog and dew over all of nature, because here Xin  and Fei  spread the Essence of food and water to moisten and nourish the entire body. The Miraculous Pivot says, “The Upper Jiao opens outward, spreads the five tastes of the food Essence, pervades the skin, fills the body” . If exogenous pathogens invade the Upper Jiao, they will present as dysphoria, palpitations, cough, and chest heaviness. |
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| (b) | The Middle Jiao, located in the epigastrium between the diaphragm and the umbilicus, includes the Pi, Stomach, and Pancreas. Food, digested by the Pi and Stomach, softens, dissolves, and ferments. The Miraculous Pivot says, “The Middle Jiao receives Qi expels the wastes, steams the body fluid, and links to the Fei” If pathogens attack the Middle Jiao, they will present as distending fullness of the upper abdomen, vomiting, diarrhea, and jaundice. | |
| (c) | The Lower Jiao, located below the umbilicus, includes the Shen, Bladder, Gan, and Large and Small Intestines. According to its anatomical location, Gan should belong to the Middle Jiao, but since it shares the same source as Shen  , TCM places it in the Lower Jiao. The Miraculous Pivot says, “The Lower Jiao oozes down, secretes the fluids, and transmits them to the Bladder” , or acts as a sewer to filter and drain off waste. If pathogens attack the Lower Jiao, they will present as oliguria, frequent urination, urgent urination, and dysuria. |
(3) Relationship with the pericardium
San Jiao and the Pericardium are interiorly–exteriorly related, but in an extremely tenuous fashion. TCM accepts only five Zang and six Fu organs; so, while the Pericardium has a meridian, it is not an independent Zang organ. Thus, the Pericardium is more applicable to the channels, rather than to the interaction of the organs. Because Xin is so important viscera, the Pericardium is the protect organ for Xin — a membrane around Xin. When pathogenic factors invade Xin, they first attack the Pericardium.