Meridian (Chinese medicine)
Main concepts 
There are about 400 acupuncture points and 20 meridians connecting most of the points, however by the 2nd Century CE, 649 acupuncture points were recognized in China. These 20 meridians include the "twelve regular channels" or "twelve regular meridians", with each meridian corresponding to each organ; nourishing it and extending to an extremity. There are also "Eight Extraordinary Channels" or meridians, two of which have their own sets of points, and the remaining ones connecting points on other channels.
Twelve standard meridians 
The twelve standard meridians, also called Principal Meridians, are divided into Yin and Yang groups. The Yin meridians of the arm are: Lung, Heart, and Pericardium. The Yang meridians of the arm are: Large Intestine, Small Intestine, and Triple Warmer. The Yin Meridians of the leg are 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 twelve standard meridians:
|Meridian name (Chinese)||Yin / Yang||Hand / Foot||5 elements||Organ||Time of Day|
|Taiyin Lung Channel of Hand (手太阴肺经) or Taiyin Lung Meridian of Hand||Taiyin (greater yin)||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 Shaoyin Heart Meridian of Hand||Shaoyin (lesser yin)||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 Jueyin Pericardium Meridian of Hand||Jueyin (absolute yin)||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 Shaoyang Sanjiao Meridian of Hand||Shaoyang (lesser yang)||Hand (手)||Fire (火)||Triple Heater (三焦)||亥 [hài]
9 p.m. to 11 p.m.
|Taiyang Small Intestine Channel of Hand (手太阳小肠经) or Taiyang Small Intestine Meridian of Hand||Taiyang (greater yang)||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 Yangming Large Intestine Meridian of Hand||Yangming (yang brightness)||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 Taiyin Spleen Meridian of Foot||Taiyin (greater yin)||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 Shaoyin Kidney Meridian of Foot||Shaoyin (lesser yin)||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 Jueyin Liver Meridian of Foot||Jueyin (absolute yin)||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 Shaoyang Gallbladder Meridian of Foot||Shaoyang (lesser yang)||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 Taiyang Bladder Meridian of Foot||Taiyang (greater yang)||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 Yangming Stomach Meridian of Foot||Yangming (yang brightness)||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, T'ai chi ch'uan and Chinese alchemy. These eight extra meridians are different to 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 or internal organs. These channels were first systematically referred to 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) by Li Shi Zhen 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]
Criticism of traditional Chinese meridian theory 
In 1694, during the "quarrel of the Ancients and Moderns", after having seen some meridian diagrams from the Lèi Jīng and misinterpreting them as anatomical drawings, British Scholar William Wotton wrote this famous criticism of TCM:
- It would be tedious to dwell any longer upon such Notions as these, which every page of Cleyer's book is full of. The Anatomical Figures annexed to the Tracts, which also were sent out of China, are so very whimsical, that a Man would almost believe the whole to be a Banter, if these Theories were not agreeable to the occasional hints that may be found in the Travels of the Missionaries. This, however, does no prejudice to their [Medicinal Simples], which may, perhaps, be very admirable, and which a long Experience may have taught the Chineses to apply with great success; and it is possible that they may sometimes give not unhappy Guesses in ordinary Cases, by feeling their Patients Pulses: Still, this is little to Physic, as an Art; and however, the Chineses may be allowed to be excellent Empiricks, as many of the West-Indian Salvages [Savages] are, yet it cannot be believed that they can be tolerable Philosophers; which, in an Enquiry into the Learning of any Nation, is the first Question that is to be considered.
See also 
- Acupuncture point
- List of acupuncture points
- Marma adi
- Nadi (yoga)
- Pressure points
- Glossary of alternative medicine
- Standard Acupuncture Nomenclature, World Health Organization
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