Oversimplifying the name of the 12 meridian channels

The meridian system, also known as the channel system, is an essential concept for diagnosis and treatment in acupuncture practice within traditional East Asian medicine.¹ The World Health Organization (WHO) began promoting standardization of acupuncture practice in the 1980s. A standardized nomenclature for 361 acupoints and 12 major meridians was released by the WHO Regional Office for the Western Pacific (WPRO) in 1984.² Eleven meetings were held over a 5-year period, and a consensus on the locations of all 361 acupoints was reported in 2008.³ Before the development of the standardized nomenclature, there were various ways to express the entire names of the meridians. The original names of the meridians were taught to acupuncture practitioners with the use of Pinyin. For instance, Shoutaiyang xiaochangjing in Pinyin (a phonetic tool to represent the sounds of Chinese character using the Latin alphabet) is equivalent to Small Intestine meridian in English.⁴ The WHO Regional Working Group on the Standardization of Acupuncture Nomenclature advised that the alphanumeric code be generated from the English translation of the meridian names because English is the primary language used for worldwide medical science communication.⁴ The names of these acupuncture points are based on their corresponding meridian names. For instance, the fourth acupoint along the Large Intestine meridian is denoted LI4. Practitioners and researchers have been urged to use the WHO standard nomenclature to boost the reliability and repeatability of acupuncture studies.⁵ However, the names of the 12 meridian channels are now being reconsidered.⁶

The original names are based on various factors, including the differentiation between extremities (hands vs. feet), the division of body regions (three Yin vs. three Yang areas), and the association with specific internal organs (solid vs. hollow organs). The names of the hand or foot meridians are typically derived by their position with respect to the beginning or end of the meridian. In addition, the anterior or medial side of the arm or leg (Yin side) is split into three regions (TaiYin, JueYin, and ShaoYin), and the posterior or lateral side of the arm or leg (Yang side) is separated into three regions (YangMing, ShaoYang, and TaiYang) (Fig. 1). Moreover, each meridian has connections to internal organs. The five visceral (solid) organs are the liver, lungs, kidneys, spleen, and heart, and the six hollow organs are the gallbladder, stomach, small, and large intestine, and triple energizer (SanJiao). Notably, standardized meridian names typically include only the name of the internal organ associated with the meridian (e.g., Large Intestine meridian) rather than the full name that specifies both the organ and its location (e.g., Hand YangMing Large Intestine meridian). This lack of crucial information in meridian names may result in insufficient details or lead to potential misunderstandings regarding the clinical characteristics of meridians.⁷

Fig. 1.

Incorporation of three Yin and three Yang regions into the meridian name. Three distinctive areas in the arm and leg are named by three Yin and three Yang regions. The anterior side of the arm or leg (Yin side) can be split into three regions: TaiYin, JueYin, and ShaoYin (anterior view, left side of figure), and the posterior side of the arm or leg (Yang side) can be separated into three regions: YangMing, ShaoYang, and TaiYang (posterior view, right side of figure).

The book HuangDi NeiJing (The Yellow Emperor's Classic of Internal Medicine) states that “The twelve channels internally connect the internal organs and externally link with the joints and limbs,” suggesting that the entire body is interconnected through these internal and external connections as well as through the upward and downward distribution of the channels. The origin of the meridian system suggests that meridians also serve as connections between the treatment site and the disease site (e.g., the Large Intestine meridian is believed to originate from the connection between LI4 and the teeth). Hence, this system provides empirical clinical data to guide the selection of appropriate acupoints for the treatment of specific ailments.⁸ Main acupoints along the Yin meridian, which internally link to the visceral organs, are primarily used to treat the five visceral organs and the six hollow organs. By contrast, main acupoints along the Yang meridian, which externally link to the joints and limbs, are mainly used to treat various diseases associated with the routes of the corresponding meridians.⁹ For instance, HT5 and PC6 in the Heart and Pericardium meridians specifically reduce the frequency of angina attacks in patients with chronic stable angina.¹⁰ SI3 has been used to treat shoulder pain, which is associated with the route of the Small Intestine meridian¹¹ (Fig. 2). The Hand TaiYang Small Intestine meridian, which was originally called the Shoulder meridian, is externally connected to the shoulder regions rather than internally connected to the small intestine.⁸ Similarly, the Hand YangMing Large Intestine meridian, which was originally called the Tooth meridian, is externally connected to the tooth and nose regions rather than internally connected to the large intestine. When a meridian's name contains the division of bodily regions, such as TaiYang or YangMing, it provides information about the dispersion of the channels and further connections between the treatment site and the disease site. When we refer to the Small Intestine meridian as the Hand TaiYang Small Intestine meridian, we maintain the clinical significance of the meridian system and correctly utilize acupoints.

Fig. 2.

Relationship between acupoints and target disease areas. Main acupoints in the Yin meridian are recommended to treat visceral diseases, whereas main acupoints in the Yang meridian are recommended to treat somatic diseases. HT5 and PC6 in the Heart and Pericardium meridians specifically reduce the frequency of angina attacks in patients with chronic stable angina. SI3, an acupoint in the Small Intestine meridian, has been used to treat shoulder pain located along the route of the corresponding meridian. The figures were created using BioRender (www.biorender.com).

In this article, we are not advocating for the Small Intestine meridian to be referred to as the Hand TaiYang Small Intestine meridian. Instead, our recommendation is that acupuncture practitioners and researchers remember the names of the meridians to avoid any confusion regarding the connection between acupoints and the targeted locations of the illnesses. In this context, the main acupoints along the Yin meridians, which have internal connections to the visceral organs, are used for visceral diseases (such as visceral pain), whereas the main acupoints along the Yang meridians, which have external connections to the joints and limbs, are used for somatic diseases (such as musculoskeletal pain). We believe that it is crucial to consider the comprehensive meaning of the meridian name for successful acupoint selection.

CRediT authorship contribution statement

In-Seon Lee: Conceptualization, Writing – review & editing. Yeonhee Ryu: Writing – original draft, Writing – review & editing. Younbyoung Chae: Conceptualization, Writing – original draft, Writing – review & editing.