BL-57 (Cheng Shan) Mountain Support

What does BL-57 Cheng Shan do?

Cheng Shan BL-57 does two things that look unrelated until you follow the channel: it relaxes the sinews of the calf, and it is the classical distal point for haemorrhoids and the anal region. Sacred Lotus sources & references record both, and both follow from the same fact — the Bladder channel of Foot Tai Yang runs down the back from the sacrum and the anal region through the back of the thigh and into the calf, and BL-57 sits at the point where the two bellies of the calf muscle part. It is also one of the twelve Ma Dan-yang Heavenly Star points, the short list of points a practitioner was expected to be able to treat almost anything with.

• Relaxes the sinews, activates the channel and alleviates pain — the first action in our own record and the everyday one. It is the point for cramp and spasm of the calf, for the tight, gripping pain that seizes the back of the lower leg, and for pain anywhere along the Bladder channel's course down the back of the body.
• Benefits the calf and the heel — the local action, extending to the Achilles tendon and the heel below it, which lie on the same line.
• Treats haemorrhoids and benefits the anus — the action for which the point is most famous and the one that makes it distinctive. Our own record already noted BL-57 as a distal point for haemorrhoids. It is used for haemorrhoids themselves, for pain and swelling after anal surgery, for prolapse of the rectum, for anal fissure and for constipation, none of which is a calf complaint. The basis is channel course, not proximity.
• Relieves lumbar and back pain — as a distal point on the Bladder channel, which runs the length of the back. A documentary study of the classical literature found that the disorders most often recorded for this point, alone or in combination, were disorders of the limbs and channels (PMID 36301172).
• Regulates the intestines — the recorded basis for its use in constipation, and the reason it appears in prescriptions for the lower bowel alongside its anal indications.

Why is a point on the calf used for the anal region?

Because the Bladder channel is the one channel that connects the two. Of the twelve channels, Foot Tai Yang is the one that descends the whole back of the body: it passes down either side of the spine, crosses the sacrum and the buttock — where Bai Huan Shu BL-30 and Hui Yang BL-35 lie, both close to the anal region — and continues down the back of the thigh through Wei Zhong BL-40 into the calf. BL-57 is the distal point of that line at which the classical sources locate the anal function. This is a channel relationship in the strict sense: an internal connection asserted by the channel's documented pathway, not an inference from where the point happens to sit. It is what allows a practitioner to treat the anal region without going near it, and it is why BL-57 is present in almost every modern acupuncture protocol for haemorrhoid surgery.

Source: Sacred Lotus sources & references (existing action and use records; channel and Heavenly Star classification queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 314); Chinese Acupuncture & Moxibustion (p. 188); PMID 36301172; cross-referenced against multiple online sources.

What is BL-57 Cheng Shan used for?

Cheng Shan BL-57 is used above all for two things: cramp and spasm of the calf, and haemorrhoids. The indications carried in Sacred Lotus sources & references are low back pain, spasm of the gastrocnemius, haemorrhoids, constipation and beriberi, with the point recorded as a distal point for haemorrhoids; the standard reference literature and the classical documentary record set them out more fully below. These describe traditional use, not proven treatment.

• Cramp and spasm of the calf muscles
• Tightness, stiffness and pain of the back of the lower leg
• Haemorrhoids, including bleeding and prolapsed haemorrhoids
• Pain, swelling and distension after haemorrhoid surgery
• Anal fissure and anal pain
• Prolapse of the rectum
• Constipation
• Low back pain and lumbar stiffness
• Pain along the back of the thigh and leg (sciatic distribution)
• Heel pain and Achilles tendon pain
• Weakness, heaviness or difficulty in lifting the foot
• Swelling of the lower leg
• Beriberi (the classical indication, recorded in the reference literature)
• Trembling of the leg and difficulty standing for long

Source: Sacred Lotus sources & references (existing indication and use records); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 314); Chinese Acupuncture & Moxibustion (p. 188); classical indication record per PMID 36301172.

Where is BL-57 Cheng Shan, and how is it used in practice?

Cheng Shan lies on the back of the lower leg, on the midline, in the pointed hollow that appears where the two bellies of the calf muscle divide — about eight cun below Wei Zhong BL-40 at the back of the knee, roughly midway between BL-40 and Kun Lun BL-60 at the ankle. Sacred Lotus sources & references give it in both terms. The hollow is not always obvious at rest; the standard locating instruction is to have the person stretch the leg or lift the heel, which draws the calf muscle taut and makes the inverted V where the two bellies part clearly visible. That shape is what the name describes.

In practice BL-57 is used in two quite separate settings, and a reader is likely to arrive at this page from one or the other. Among practitioners of musculoskeletal work it is the calf point — for cramp, for tight calves, for pain running down the back of the leg. In anorectal practice it is the standard distal point, and it is the point that appears in essentially every published acupuncture protocol for pain after haemorrhoid surgery. Both uses are old and both are documented.

Which points is BL-57 combined with?

• With Kun Lun BL-60 — the most frequently recorded partner in the classical literature. A study of 1,156 classical medical books found Kunlun BL-60 to be the auxiliary point most often paired with Chengshan, with the Bladder channel itself the most frequently combined channel (Gu Y et al., Zhen Ci Yan Jiu 2022;47(10):927–32, PMID 36301172).
• With Er Bai — the extra point on the forearm, BL-57's constant partner for haemorrhoids and the one point paired with it in every modern anorectal study located. The two are used together so consistently that Er Bai has almost no research history apart from BL-57.
• With Chang Qiang DU-01 — the local point at the tip of the coccyx, giving a local-and-distal treatment of the anal region. A randomised trial of acupoint thread-embedding after mixed-haemorrhoid surgery used exactly this pairing, Changqiang DU-01 with bilateral Chengshan BL-57 (Zhongguo Zhen Jiu 2026;46(5):738–742, PMID 42116778).
• With Da Chang Shu BL-25 — the Large Intestine's Back-Shu point, added for the bowel; BL-57, BL-25 and Er Bai together form the prescription tested in the post-operative electroacupuncture trial noted below (PMID 29318862).
• With Xia Liao BL-34 — in the fourth sacral foramen, the pairing used in the electroacupuncture preconditioning trial for pain after haemorrhoidectomy (PMID 31099217).
• With Wei Zhong BL-40 — the He-Sea point at the back of the knee, on the same line above it; BL-40 is the classical command point of the back and the two are used together for lumbar and posterior-leg pain.
• With Cheng Jin BL-56 — "Sinew Support", immediately above BL-57 on the same line. The two names are a pair, and the points are used together for the calf.
• With Tiao Kou ST-38 — the classical through-needling from Tiaokou on the front of the leg toward Chengshan behind it, used not for the leg at all but for frozen shoulder. Sixty patients were randomised to that technique with or without active shoulder movement during treatment, with both groups improving and the movement group improving more (Zhongguo Zhen Jiu 2018;38(8):815–8, PMID 30141290). It is one of the better-known pieces of distal-point technique in the repertoire.
• With Fei Yang BL-58 — the Luo-Connecting point of the Bladder channel, just below and lateral to BL-57, added where the channel connection to the Kidney channel is wanted.

Where does BL-57 sit among the Ma Dan-yang Heavenly Star points?

The Heavenly Star points are a set of twelve named in a verse attributed to the Jin-dynasty physician Ma Dan-yang, selected as the small number of points with which the widest range of disorders could be treated. Sacred Lotus sources & references hold the complete set of twelve, and BL-57 is one of them:

• Lie Que LU-07
• He Gu LI-04
• Qu Chi LI-11
• Zu San Li ST-36
• Nei Ting ST-44
• Tong Li HT-05
• Wei Zhong BL-40
• Cheng Shan BL-57 — this page
• Kun Lun BL-60
• Huan Tiao GB-30
• Yang Ling Quan GB-34
• Tai Chong LIV-03

Three of the twelve sit on the Bladder channel of the leg — Wei Zhong BL-40, Cheng Shan BL-57 and Kun Lun BL-60 — running down the back of the leg in that order, and the classical verse records much the same ground for all three: the lumbar region, the back of the leg, and in Cheng Shan's case the anal region as well. That three of a set of twelve fall on one line of one channel is a comment on how much of the classical repertoire for back and leg pain lives on the Bladder channel.

Source: Sacred Lotus sources & references (BL-57 record; the full set of twelve Ma Dan-yang Heavenly Star points and the neighbouring points queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 314); Chinese Acupuncture & Moxibustion (p. 188); PMID 36301172; PMID 42116778; PMID 29318862; PMID 31099217; PMID 30141290; cross-referenced against multiple online sources.

Where is BL-57 located?

• A Manual of Acupuncture (p. 314): On the lower leg, in the depression formed below the bellies of the gastrocnemius muscle when the muscle is flexed, approximately 8 cun distal to Weizhong BL-40, i.e. midway between Weizhong BL-40 and Kunlun BL-60.
• Chinese Acupuncture and Moxibustion (p. 188): On the posterior midline of the leg, between Weizhong (BL-40) and Kunlun (BL-60), in a pointed depression formed below the gastrocnemius muscle belly when the leg is stretched or the heel is lifted.

How is BL-57 Cheng Shan needled?

Reference fact: the standard texts record perpendicular insertion at Cheng Shan, with Sacred Lotus sources & references giving 0.8 to 1.2 inch and moxibustion applicable, and Deadman & Al-Khafaji (p. 314) and Chinese Acupuncture & Moxibustion (p. 188) recording a comparable perpendicular range. These figures are recorded here as neutral reference data describing what the textbooks state. They are not instruction, and this page does not teach technique. Needling is carried out only by a qualified, licensed practitioner.

What lies beneath the point

• This is a comparatively low-hazard point, and it is worth saying so directly rather than attaching a generic warning. BL-57 lies in the muscle mass of the calf. There is no lung, no viscus and no great vessel of the trunk anywhere in reach, and the standard references attach no special prohibition to it. It carries none of the anatomical exposure of the thoracic Bladder points such as Fei Shu BL-13 or Ge Shu BL-17 over the lung, of Jian Jing GB-21 over the lung apex, or of Feng Fu DU-16 at the base of the skull. The depth our own record gives — up to 1.2 inch — is roughly twice what is recorded for the points over the thorax, and that difference is itself the safety statement: depth figures in this literature track the structure underneath.
• The structures that are present. The needle passes through skin and subcutaneous tissue into the two heads of gastrocnemius at the point where they meet, and beneath them lies soleus. Running superficially in this region are the sural nerve and the small saphenous vein, both close to the midline of the calf. Deeper, beneath soleus, lies the deep posterior compartment carrying the tibial nerve and the posterior tibial vessels. Contact with a cutaneous nerve produces a sharp, electric sensation rather than injury, and the reference literature treats this as an ordinary caution of technique rather than as a hazard.
• The calf is a muscle that cramps, which has a practical consequence. The point is used for calf spasm, and needling a muscle that is prone to spasm can provoke one. The reference literature records this as a technique consideration rather than a complication.
• What the classical record specifies. The documentary study of 1,156 classical books found 71 passages describing needling and moxibustion technique at this point across seven methods, and recovered two consistent figures: moxibustion of five cones per session, and a needling depth of about seven fen — roughly seven-tenths of a cun (Gu Y et al., Zhen Ci Yan Jiu 2022;47(10):927–32, PMID 36301172). It is unusual to be able to state what a classical consensus depth actually was, and this point is one of the few where a study has recovered it.
• Moxibustion is recorded as applicable, and the modern anorectal literature uses electroacupuncture, transcutaneous stimulation, catgut or thread embedding and non-needle pressure at this point as often as plain needling.

The general safety picture

For context rather than alarm: a meta-analysis of prospective clinical studies estimated serious adverse events from acupuncture at approximately 1 per 10,000 patients and around 8 per million treatments, with about half of all recorded events being bleeding, pain or flare at the needle site, and concluded that acupuncture is among the safer treatments in medicine (Bäumler P et al., BMJ Open 2021;11:e045961, PMID 34489268, DOI 10.1136/bmjopen-2020-045961). The serious events recorded in that literature cluster at a small number of anatomically exposed points — chiefly over the thorax and at the base of the skull — and BL-57 is not among them. The sham-controlled and randomised studies at this point described under the notes below, several of them in post-surgical patients, report no serious adverse events.

Source: Sacred Lotus sources & references (existing needling record); Deadman & Al-Khafaji, A Manual of Acupuncture (p. 314); Chinese Acupuncture & Moxibustion (p. 188); PMID 36301172; PMID 34489268 — each verified resolvable and checked for retraction status before citation.

What does the name Cheng Shan mean?

Cheng Shan means "Mountain Support" — cheng, to support, bear or hold up, and shan, a mountain. The name is a picture of the anatomy. When the calf is tensed, the two bellies of the gastrocnemius stand out as a pair of rounded masses with a cleft between them, and the shape the tradition saw there was a mountain with a valley below it; the point sits in the hollow where the mountain is supported from beneath. Sacred Lotus sources & references translate the name as Mountain Support. It is also recorded under the names Yu Fu, "Fish Belly", and Rou Zhu, "Fleshy Pillar" — both descriptions of the same shape from a different angle, and both useful confirmations that the name is anatomical rather than metaphorical.

Is BL-57 the point for haemorrhoids?

It is the principal channel point for the anal region, and this is worth stating plainly, because the credit is sometimes given to points that have no channel basis for it. The extra point Er Bai on the forearm is the clearest case. Er Bai is a real and well-attested point for haemorrhoids, and it is used constantly — but it lies on no channel, carries no five-shu, yuan, luo, xi-cleft, back-shu or front-mu classification, and has no channel connection to the anal region. Our own record for Er Bai previously described it as "lifting sinking qi" and "stopping bleeding"; both are organ and channel-theory phrases and both have been removed. The points that genuinely carry the anal region in channel terms are Chang Qiang DU-01 at the tip of the coccyx, Bai Huan Shu BL-30 on the sacrum, and Cheng Shan BL-57 here on the calf — all three on channels that traverse the region — while Bai Hui DU-20 at the vertex is the point classically credited with raising sinking qi in prolapse. This page is the other half of that correction. Cheng Shan carries the anal action because the Bladder channel of Foot Tai Yang runs from the sacral and anal region down the back of the leg through this point, which is a channel relationship rather than an inference. A reader who arrived searching for "the acupuncture point for haemorrhoids" has arrived at the right one.

Is there research on BL-57 Cheng Shan?

BL-57 has more point-specific research attached to it than most points on the leg, and unusually the research is concentrated on its anal indication rather than its calf one — including a documentary study of the classical record and a series of randomised trials in patients recovering from haemorrhoid surgery. The honest limitation is that every clinical trial located uses BL-57 inside a small prescription, so the results describe the prescription.

• Documentary study of the classical record. Researchers searched a collection of 1,156 classical Chinese medical books for every passage concerning Chengshan BL-57 and included 196 passages from 61 books. These covered 56 disorders or syndromes across internal medicine, surgery, paediatrics, ophthalmology and ear-nose-throat practice, with 174 passages on indications and 71 on technique across seven treatment methods. The disorders most frequently recorded, whether the point was used alone or in combination, were disorders of the limbs and channels; the most frequently paired point was Kunlun BL-60 and the most frequently paired channel the Bladder channel itself; the consensus moxibustion dose was five cones and the consensus needling depth about seven fen (Gu Y et al., Zhen Ci Yan Jiu 2022;47(10):927–32, PMID 36301172, DOI 10.13702/j.1000-0607.20210777). This is the single most informative piece of research on the point, and it is worth noting that the classical record weights the limb-and-channel uses more heavily than the anal ones, which is the reverse of the modern research literature.
• Electroacupuncture after haemorrhoid surgery. A randomised trial in 60 patients applied electroacupuncture at Chengshan BL-57, Dachangshu BL-25 and Er Bai for thirty minutes daily over three days after surgery for mixed haemorrhoids, reporting greater improvement in anal pain, a sense of anal distension and bleeding on days two and three than basic care alone (Zhen Ci Yan Jiu 2017;42(6):533–536, PMID 29318862). Three points stimulated together, so no part of the effect can be assigned to BL-57 alone.
• Electroacupuncture before surgery, comparing frequencies. One hundred and twenty patients were randomised to three electroacupuncture waveforms applied at Xialiao BL-34 and Chengshan BL-57 for thirty minutes before Milligan-Morgan haemorrhoidectomy. All three reduced post-operative anal pain; the 2 Hz/100 Hz dilatational wave produced lower visual-analogue pain scores, better limb-activity scores and a lower requirement for oral analgesia at 24 hours than either continuous wave (Zhongguo Zhen Jiu 2019;39(5):477–81, PMID 31099217). A reasonable size, but it compares stimulation parameters rather than acupuncture against no acupuncture.
• Acupoint thread embedding after surgery. Sixty-eight patients scheduled for mixed-haemorrhoid surgery were randomised to routine post-operative care alone or with thread embedding at Changqiang DU-01 and bilateral Chengshan BL-57. Pain, perianal oedema, wound exudate, state anxiety and sleep-quality scores were lower in the treated group at days three and seven, with an effective rate of 90.6 per cent against 61.3 per cent (Zhongguo Zhen Jiu 2026;46(5):738–742, PMID 42116778). Two points, and an untreated rather than sham comparator.
• Non-needle pressure, with a genuine sham. A patient- and assessor-blinded randomised trial in 154 patients used pestle-needle pressure at Yao Shu DU-02, Ming Men DU-04, Chang Qiang DU-01, Chengshan BL-57, Er Bai and perianal positions against a light-pressure sham, reporting lower pain scores after haemorrhoidectomy (J Integr Med 2020;18(6):492–498, PMID 32798197). The best-designed of the group because it carried a real sham control — but six sites were stimulated at once and no needles were used.
• Transcutaneous stimulation after surgery. A randomised controlled study in 80 patients gave four twenty-minute sessions of transcutaneous acupoint electrical stimulation at Chengshan BL-57 and Er Bai, reporting lower pain and anxiety scores and some heart-rate-variability differences against no stimulation (Clin Nurs Res 2018;27(4):450–466, PMID 28071133). Two points, and an untreated control.
• Mechanism work at the point. A rat study of post-operative anal pain examined muscarinic acetylcholine receptors and the IP3–Ca²⁺–calmodulin pathway, reporting that electroacupuncture at Chengshan reduced pain sensitivity in parallel with suppression of that signalling cascade (Song Y et al., Clinics (São Paulo) 2024;79:100485, PMID 39316895, PMC11462218). An animal study, and one for which the journal subsequently published an erratum — recorded here with that stated rather than omitted.
• The calf itself. The musculoskeletal side of the point has been studied mostly in animals: electroacupuncture at Chengshan has been examined for gait recovery and satellite-cell proliferation after blunt trauma to the gastrocnemius (Zhongguo Zhen Jiu 2023, PMID 37697870) and for apoptosis-related protein expression in denervated gastrocnemius muscle (Zhen Ci Yan Jiu 2017, PMID 29072010). These are preclinical and are noted for completeness.

What is missing should be said plainly: there is no trial of BL-57 alone, and — more pointedly — no study located tests it for haemorrhoids themselves as opposed to recovery after haemorrhoid surgery. The traditional indication and the researched indication are not the same thing, and that gap is worth knowing about. Nor has the point's commonest everyday use, calf cramp, been tested in humans at all.

How does BL-57 compare with the points around it?

Cheng Jin BL-56, "Sinew Support", lies immediately above it on the same line and is the nearer neighbour in both name and function, though far less used. He Yang BL-55 sits higher still just below the knee crease, and Fei Yang BL-58 just below and lateral to Cheng Shan is the Luo-Connecting point of the Bladder channel, the point to choose when the connection to the Kidney channel is wanted. Wei Zhong BL-40 at the back of the knee is the He-Sea point and the classical command point of the back; BL-40 and BL-57 are used together constantly for lumbar and posterior-leg pain, and both are Heavenly Star points. Kun Lun BL-60 at the outer ankle completes that trio and is the partner point the classical literature records most often with Cheng Shan. For the anal region, Chang Qiang DU-01 at the coccyx is the local point, Bai Huan Shu BL-30 and Hui Yang BL-35 are the sacral points of the same group, and Er Bai on the forearm is BL-57's constant partner — an extra point rather than a channel point, as set out above, and the easiest of the group to reach because it requires nothing to be uncovered.

Source: Deadman & Al-Khafaji, A Manual of Acupuncture (p. 314); Chinese Acupuncture & Moxibustion (p. 188); Sacred Lotus sources & references (BL-57 record; the Heavenly Star set, the neighbouring Bladder-channel points, the sacral and anal-region points and the Er Bai extra-point record queried directly); PMID 36301172; PMID 29318862; PMID 31099217; PMID 42116778; PMID 32798197; PMID 28071133; PMID 39316895 (PMC11462218); PMID 37697870; PMID 29072010; PMID 30141290 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.