BL56 (Chengjin, “Support the Sinew”) is an acupuncture point on the Bladder Meridian. It is located on the posterior lower leg, in a depression at the center of the belly of the gastrocnemius muscle, approximately midway between Weizhong (BL40) and Chengshan (BL57). Classically described as being 7 cun superior to the heel. It relaxes the sinews and alleviates cramping, activates the channel and alleviates pain, treats hemorrhoids.
On the posterior lower leg, in a depression at the center of the belly of the gastrocnemius muscle, approximately midway between Weizhong (BL40) and Chengshan (BL57). Classically described as being 7 cun superior to the heel.
Perpendicular insertion 1.0 to 2.0 cun. Caution is advised to avoid deep insertion, which could injure the tibial nerve and posterior tibial artery and vein that lie deep to the gastrocnemius and soleus muscles.
Relaxes the sinews and alleviates cramping, activates the channel and alleviates pain, treats hemorrhoids.
Convulsions, leg soreness, numbness of the lower leg, cholera with muscle cramping, difficult defecation, heaviness of the leg, pain radiating to the lower abdomen, lumbar and back rigidity, hemorrhoid pain, epilepsy, madness, nasal congestion and nosebleed, axillary swelling, heel pain, leg pain.
Chengjin is a crucial local point for relaxing the powerful gastrocnemius muscle, making it highly effective for acute calf cramps, spasms, and pain. While classically needling was forbidden, its use for local muscle issues is now common. Its classical indications for hemorrhoids and difficult defecation highlight the Bladder channel's connection to the anus and its role in treating disorders of the lower jiao.
Classical text; the translation was prepared with AI and is not clinical advice.
《針方六集》 Zhēnfāng Liùjí — Six Collections on Needling, Wu Kun, 1618 · 卷之五·紛署集 · 足太陽及股並陽蹻六穴凡三十六穴第三十四 · Source: jicheng.tw ↗
承筋二穴，主寒痹轉筋，陰股腫，腳腨酸，小腹痛，大便難，背脹腰痛，頭痛，鼽衄，痔瘡，腳跟急痛The text records that BL56 was used for cold-bi with cramping of the sinews, swelling of the inner thigh, aching calves, lower abdominal pain, difficult defecation, back distension and lumbar pain, headache, nosebleed, haemorrhoids and acute heel pain.
《針灸逢源》 Zhēnjiǔ Féngyuán — Sources of Acupuncture & Moxibustion, Li Xuechuan, 1815 · 卷四 · 經穴考正 · 足太陽膀胱經穴考 · Source: jicheng.tw ↗
承筋（一名腨腸一名直腸） 在腨腸中央陷中。 脛後從腳跟上七寸（灸三壯禁針）治腨酸腳跟痛According to this text, BL56 lies in the hollow at the middle of the calf, 7 cun above the heel; it states 3 moxa cones and that needling is prohibited, and records use for aching calves and heel pain.
《神灸經綸》 Shénjiǔ Jīnglún — Principles of Divine Moxibustion, Wu Yiding, 1851 · 卷之二 · 十二經脈起止 · 膀胱經六十三穴分寸 · Source: jicheng.tw ↗
承筋（一名腨腸一名直腸） 從合陽下行腨腸中央陷中腳跟上七寸灸三壯According to this text, BL56 is reached by going down from BL55 to the hollow at the centre of the calf, 7 cun above the heel, and 3 moxa cones are applied.
《針灸甲乙經》 Zhēnjiǔ Jiǎyǐ Jīng — Systematic Classic of Acupuncture & Moxibustion, c. 256–282 · 卷08 · Source: Wikisource ↗
寒熱篡後出，瘈瘲，腳酸重，戰栗不能久立，腳急腫，跗痛足筋攣，少腹引喉嗌，大便難，承筋主之The text records that BL56 was used for chills and fever with prolapse behind the perineum, convulsions, aching heavy legs, shivering with inability to stand long, swollen tight feet, cramped foot sinews, lower abdominal pain pulling to the throat, and difficult defecation.
BL56 is one of 67 points on the Bladder Meridian. Nearby points:
BL56 (Chengjin) is located on the posterior lower leg, in a depression at the center of the belly of the gastrocnemius muscle, approximately midway between Weizhong (BL40) and Chengshan (BL57). Classically described as being 7 cun superior to the heel.
BL56 relaxes the sinews and alleviates cramping, activates the channel and alleviates pain, treats hemorrhoids. Common clinical indications include convulsions, leg soreness, numbness of the lower leg, cholera with muscle cramping, difficult defecation, heaviness of the leg, pain radiating to the lower abdomen, lumbar and back rigidity, hemorrhoid pain, epilepsy, madness, nasal congestion and nosebleed, axillary swelling, heel pain, leg pain.
Perpendicular insertion 1.0 to 2.0 cun. Caution is advised to avoid deep insertion, which could injure the tibial nerve and posterior tibial artery and vein that lie deep to the gastrocnemius and soleus muscles. Caution: The Jia Yi Jing, Qian Jin Yao Fang, and Zhen Jiu Ju Ying all state that this point is contraindicated for needling ('禁針' or '禁不可刺').
BL56 is a point on the Bladder Meridian (Zú Tài Yáng Páng Guāng Jīng).