meridian (chinese medicine) meridian (chinese medicine) the meridian system (simplified chinese: 经络; traditional chinese: 經絡; pinyin: jīngluò, also called channel network) is a concept in traditional chinese medicine (tcm). meridians are paths through which the life-energy known as "qi" (ch'i) flows. meridian system this article is part of a series onalternative medicine general information alternative medicine history terminology alternative veterinary medicine quackery (health fraud) rise of modern medicine pseudoscience antiscience skepticism scientific therapeutic nihilism fringe medicine and science acupressure acupuncture alkaline diet anthroposophic medicine apitherapy applied kinesiology aromatherapy association for research and enlightenment auriculotherapy bates method black salve bodywork bone-setting bowen technique breathwork camel urine fake covid-19 treatments cancer treatments charcoal cleanse chelation therapy chiropractic chiropractic treatment techniques vertebral 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fatigue aerotoxic syndrome candida hypersensitivity chronic lyme disease electromagnetic hypersensitivity heavy legs leaky gut syndrome multiple chemical sensitivity wilson's temperature syndrome meridians are not real anatomical structures: scientists have found no evidence that supports their existence. one historian of medicine in china says that the term is "completely unsuitable and misguided, but nonetheless it has become a standard translation." major proponents of their existence have not come to any consensus as to how they might work or be tested in a scientific context. history the concept of meridians are first attested in two works recovered from the mawangdui and zhangjiashan tombs of the han-era changsha kingdom, the cauterization canon of the eleven foot and arm channels (足臂十一脈灸經, zúbì shíyī mài jiǔjīng) and the cauterization canon of the eleven yin and yang channels (陰陽十一脈灸經, yīnyáng shíyī mài jiǔjīng). in the texts, the meridians are referenced as mài (脈) rather than jīngmài. main concepts the meridian network is typically divided into two categories, the jingmai (經脈) or meridian channels and the luomai (絡脈) or associated vessels (sometimes called "collaterals"). the jingmai contain the 12 tendinomuscular meridians, the 12 divergent meridians, the 12 principal meridians, the eight extraordinary vessels as well as the huato channel, a set of bilateral points on the lower back whose discovery is attributed to the ancient physician hua tuo. the collaterals contain 15 major arteries that connect the 12 principal meridians in various ways, in addition to the interaction with their associated internal organs and other related internal structures. the collateral system also incorporates a branching expanse of capillary-like vessels which spread throughout the body, namely in the 12 cutaneous regions as well as emanating from each point on the principal meridians. if one counts the number of unique points on each meridian, the total comes to 361, which matches the number of days in a year, in the moon calendar system. note that this method ignores the fact that the bulk of acupoints are bilateral, making the actual total 670. there are about 400 acupuncture points (not counting bilateral points twice) most of which are situated along the major 20 pathways (i.e. 12 primary and eight extraordinary channels). however, by the second century ad, 649 acupuncture points were recognized in china (reckoned by counting bilateral points twice). there are "12 principal meridians" where each meridian corresponds to either a hollow or solid organ; interacting with it and extending along a particular extremity (i.e. arm or leg). there are also "eight extraordinary channels", two of which have their own sets of points, and the remaining ones connecting points on other channels. 12 standard meridians the 12 standard meridians, also called principal meridians, are divided into yin and yang groups. the yin meridians of the arm are the lung, heart, and pericardium. the yang meridians of the arm are the large intestine, small intestine, and triple burner. the yin meridians of the leg are the spleen, kidney, and liver. the yang meridians of the leg are stomach, bladder, and gall bladder. the table below gives a more systematic list of the 12 standard meridians: meridian name (chinese)quality of yin or yangextremityfive elementsorgantime of day taiyin lung channel of hand (手太阴肺经) or hand's major yin lung meridiangreater yin (taiyin, 太阴)hand (手)metal (金)lung (肺)寅; yín; 3 a.m. to 5 a.m. shaoyin heart channel of hand (手少阴心经) or hand's minor yin heart meridianlesser yin (shaoyin, 少阴)hand (手)fire (火)heart (心)午; wǔ; 11 a.m. to 1 p.m. jueyin pericardium channel of hand (手厥阴心包经) or hand's absolute yin heart protector meridianfaint yin (jueyin – 厥阴)hand (手)fire (火)pericardium (心包)戌; xū; 7 p.m. to 9 p.m. shaoyang sanjiao channel of hand (手少阳三焦经) or hand's minor yang triple burner meridianlesser yang (shaoyang, 少阳)hand (手)fire (火)triple burner (三焦)亥; hài; 9 p.m. to 11 p.m. taiyang small intestine channel of hand (手太阳小肠经) or hand's major yang small intestine meridiangreater yang (taiyang, 太阳)hand (手)fire (火)small intestine (小肠)未; wèi; 1 p.m. to 3 p.m. yangming large intestine channel of hand (手阳明大肠经) or hand's yang supreme large intestine meridianyang bright (yangming, 阳明)hand (手)metal (金)large intestine (大腸)卯; mǎo; 5 a.m. to 7 a.m. taiyin spleen channel of foot (足太阴脾经) or foot's major yin spleen meridiangreater yin (taiyin, 太阴)foot (足)earth (土)spleen (脾)巳; sì; 9 a.m. to 11 a.m. shaoyin kidney channel of foot (足少阴肾经) or foot's minor yin kidney meridianlesser yin (shaoyin, 少阴)foot (足)water (水)kidney (腎)酉; yǒu; 5 p.m. to 7 p.m. jueyin liver channel of foot (足厥阴肝经) or foot's absolute yin liver meridianfaint yin (jueyin, 厥阴)foot (足)wood (木)liver (肝)丑; chǒu; 1 a.m. to 3 a.m. shaoyang gallbladder channel of foot (足少阳胆经) or foot's minor yang gallbladder meridianlesser yang (shaoyang, 少阳)foot (足)wood (木)gall bladder (膽)子; zǐ; 11 p.m. to 1 a.m. taiyang bladder channel of foot (足太阳膀胱经) or foot's major yang urinary bladder meridiangreater yang (taiyang, 太阳)foot (足)water (水)urinary bladder (膀胱)申; shēn; 3 p.m. to 5 p.m. yangming stomach channel of foot (足阳明胃经) or foot's yang supreme stomach meridianyang bright (yangming, 阳明)foot (足)earth (土)stomach (胃)辰; chén; 7 a.m. to 9 a.m. eight extraordinary meridians the eight extraordinary meridians are of pivotal importance in the study of qigong, taijiquan and chinese alchemy. these eight extra meridians differ from the standard twelve organ meridians in that they are considered to be storage vessels or reservoirs of energy and are not associated directly with the zang fu, i.e. internal organs. these channels were studied in the "spiritual axis" chapters 17, 21 and 62, the "classic of difficulties" chapters 27, 28 and 29 and the "study of the 8 extraordinary vessels" (qi jing ba mai kao), written in 1578. the eight extraordinary vessels are (奇經八脈; qí jīng bā mài): conception vessel (ren mai) – 任脈; rèn mài governing vessel (du mai) – 督脈; dū mài penetrating vessel (chong mai) – 衝脈; chōng mài girdle vessel (dai mai) – 帶脈; dài mài yin linking vessel (yin wei mai) – 陰維脈; yīn wéi mài yang linking vessel (yang wei mai) – 陽維脈; yáng wéi mài yin heel vessel (yin qiao mai) – 陰蹻脈; yīn qiāo mài yang heel vessel (yang qiao mai) – 陽蹻脈; yáng qiāo mài scientific view of meridian theory scientists have found no evidence that supports their existence. the historian of medicine in china paul u. unschuld adds that there "is no evidence of a concept of 'energy' -- either in the strictly physical sense or even in the more colloquial sense -- anywhere in chinese medical theory." some advocates of traditional chinese medicine believe that meridians function as electrical conduits based on observations that the electrical impedance of a current through meridians is lower than other areas of the body. a 2008 review of studies found that the studies were of poor quality and could not support the claims. some proponents of the primo vascular system propose that the putative primo vessels, very thin (less than 30 μm wide) conduits found in many mammals, may be a factor explaining some of the suggested effects of the meridian system. according to steven novella, neurologist involved in the skeptical movement, "there is no evidence that the meridians actually exist. at the risk of sounding redundant, they are as made up and fictional as the ether, phlogiston, bigfoot, and unicorns." the national council against health fraud concluded that "he meridians are imaginary; their locations do not relate to internal organs, and therefore do not relate to human anatomy."