ST-40 (Feng Long) Bountiful Bulge

What does ST-40 Feng Long do?

ST-40 Feng Long is the Luo (Connecting) point of the Stomach Channel of Foot Yang Ming, and it is the point the tradition calls the phlegm point — the first choice, ahead of every other point on the body, wherever a pattern is read as phlegm. That single association organises everything else about it. Phlegm in Chinese medicine is not only the sputum that is coughed up: it covers a whole class of turbid, sticky accumulation held to arise when the Spleen fails to transform fluids, and it is invoked for lumps and nodules, for dizziness and heaviness of the head, and for confusion and mania when the phlegm is said to mist the orifices of the Heart. ST-40 is used across that entire range.

• Transforms phlegm and resolves dampness — the defining action, and the one from which all its other uses are derived.
• Clears phlegm from the Lung and stops cough and wheezing — the most literal application: profuse sputum, a rattling chest, wheezing worse for damp weather.
• Clears phlegm from the Heart and calms the spirit — the recorded basis for its classical use in mania, epilepsy and disordered speech, patterns described as phlegm obstructing the Heart orifices.
• Clears phlegm from the head — for dizziness, vertigo and a heavy, muzzy, "wrapped" sensation of the head.
• Benefits the chest — for oppression, fullness and a stifling sensation in the chest.
• Dissipates nodules — the phlegm action applied to lumps, swellings and the chains of nodules the classics call scrofula.
• Descends rebellious qi — the oldest recorded action of the point, and historically the one that came first. The textual research noted below shows that the earliest indications for Feng Long were qi rising when it should be falling, and that the explicit phlegm association was built on top of it centuries later.
• Activates the channel and alleviates pain — its local role along the lower leg, for weakness, wasting and paralysis of the leg.

Source: Sacred Lotus sources & references (channel, Luo Connecting classification, existing action record); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 165; Chinese Acupuncture & Moxibustion, p. 155; Luo-point scheme per Ling Shu (Spiritual Pivot), Chapter 10; historical evolution of the indications per PubMed PMID 38986599; cross-referenced against multiple online sources.

What is ST-40 Feng Long used for?

ST-40 is used for complaints attributed to phlegm, in all the senses Chinese medicine gives that word. The indications recorded in Sacred Lotus sources & references group into four clusters — chest and breathing, head and spirit, digestion and bowel, and the local leg — and almost every entry can be traced back to the phlegm association. They describe traditional use, not proven treatment.

• Cough with profuse or difficult sputum
• Asthma and wheezing; a rattling or full chest
• Pain, oppression or a stifling sensation in the chest
• Headache, especially a heavy or muzzy head
• Dizziness and vertigo
• Mania, and disordered or excited speech
• Epilepsy
• Nausea and vomiting of phlegm; a sense of obstruction in the throat
• Constipation
• Oedema and a heavy, waterlogged sensation of the body
• Nodules, lumps and scrofula
• Muscular atrophy and motor impairment of the lower limb
• Pain, swelling or paralysis of the lower extremities
• Numbness of the leg

Source: Sacred Lotus sources & references (existing indication record); Chinese Acupuncture & Moxibustion, p. 155; Deadman & Al-Khafaji, A Manual of Acupuncture, p. 165; cross-referenced against multiple online sources.

How is ST-40 Feng Long used in practice?

Feng Long lies on the outer front of the lower leg, at the midpoint between the knee crease and the outer ankle bone — eight cun above the ankle — about two finger-breadths out from the sharp front edge of the shin bone, on the fleshy bulge of muscle that gives the point its name. It sits one finger-breadth lateral to ST-38 Tiao Kou on the same channel. The two location records held in Sacred Lotus sources & references describe the same spot from different landmarks and agree.

• With ST-36 Zu San Li — the standard within-channel pair: the He-Sea and Earth point that builds the Spleen and Stomach, joined to the Connecting point that clears what a weak Spleen has failed to transform. Treating the cause and the product together is the logic.
• With REN-12 Zhong Wan — the Front-Mu point of the Stomach and Hui-Meeting point of the Fu organs, for phlegm-damp arising in the middle burner.
• With BL-20 Pi Shu — the Back-Shu point of the Spleen, addressing the source of phlegm rather than the phlegm itself.
• With SP-03 Tai Bai — the Yuan-Luo pairing described below, the structurally correct partner for ST-40.
• With LU-05 Chi Ze and LU-07 Lie Que — for phlegm in the Lung with cough and wheezing.
• With HT-07 Shen Men, P-05 Jian Shi and DU-20 Bai Hui — for the spirit indications, where phlegm is described as clouding the Heart.
• With GB-41 Zu Lin Qi — both points carry a recorded action on phlegm nodules, and they are combined for lumps and swellings along the sides of the body.

Why does the Luo-Connecting classification matter here?

A Connecting point is where a channel throws off a branch that crosses to its interior-exterior partner. ST-40 is where the Stomach channel connects to the Spleen channel of Foot Tai Yin — and that is not a modern gloss but a statement in the Ling Shu, which names the connecting vessel of Foot Yang Ming as Feng Long, places it eight cun above the ankle, and describes its branch separating away to travel to Tai Yin. The clinical consequence is direct. The Spleen is the organ the tradition holds responsible for transforming fluids, and phlegm is what accumulates when it fails: the saying is that the Spleen is the source that makes phlegm and the Lung the vessel that stores it. ST-40's ability to reach the Spleen channel from the Stomach channel is precisely why a Stomach-channel point became the body's phlegm point. The classification is the explanation, not a label attached afterwards.

Which other Connecting points does this site hold?

Sacred Lotus sources & references hold the complete set of fifteen Connecting points: the twelve channel Luo points — LU-07 Lie Que, LI-06 Pian Li, ST-40 Feng Long, SP-04 Gong Sun, HT-05 Tong Li, SI-07 Zhi Zheng, BL-58 Fei Yang, KI-04 Da Zhong, P-06 Nei Guan, SJ-05 Wai Guan, GB-37 Guang Ming and LIV-05 Li Gou — together with REN-15 Jiu Wei, the Connecting point of the Conception Vessel, DU-01 Chang Qiang, the Connecting point of the Governing Vessel, and SP-21 Da Bao, the Great Connecting point of the Spleen. Each of the twelve is paired in use with the Source point of its partner channel, a structure called the Yuan-Luo combination. For ST-40 the partner is SP-03 Tai Bai, the Source point of the Spleen; conversely SP-04 Gong Sun, the Spleen's Connecting point, pairs with ST-42 Chong Yang, the Source point of the Stomach. Reading those two pairs side by side is the clearest way to see how the Yuan-Luo structure works.

Source: Sacred Lotus sources & references (location, Luo Connecting classification, full Connecting-point set); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 165; Chinese Acupuncture & Moxibustion, p. 155; Ling Shu (Spiritual Pivot), Chapter 10; cross-referenced against multiple online sources.

Where is ST-40 located?

• A Manual of Acupuncture (p. 165): On the lower leg, midway between the tibiofemoral joint line (level with the popliteal crease) and the lateral malleolus, two finger-breadths lateral to the anterior crest of the tibia (i.e. one finger-breadth lateral to Tiaokou ST-38).
• Chinese Acupuncture and Moxibustion (p. 155): 8 cun superior to the tip of the external malleolus, lateral to Tiaokou (ST-38) about two finger-breadth lateral to the anterior border of the tibia.

How is ST-40 Feng Long needled in the textbooks?

Reference record only — this sets out what the standard texts document, not instruction for a reader. Sacred Lotus sources & references record perpendicular insertion of 0.5 to 1.0 inch at ST-40, with moxibustion noted as applicable. Deadman & Al-Khafaji record a comparable perpendicular range extending somewhat deeper on this fleshy part of the leg. Both records agree that the insertion is perpendicular into muscle.

• Angle documented: perpendicular into the muscle belly.
• Depth documented: approximately 0.5–1.0 cun in our record; the reference literature records up to about 1.5 cun on a well-muscled leg.
• Moxibustion: documented as applicable.

Safety reference — the measured anatomy. ST-40 is one of the lower-hazard points on the body and the reason is anatomical rather than conventional: it lies in the middle of the muscular front-outer compartment of the lower leg, with no cavity, no organ and no great vessel anywhere near it. The needle enters tibialis anterior and, a little deeper and laterally, extensor digitorum longus. What bounds the recorded depth is the deep compartment beneath those muscles, where the anterior tibial artery and veins and the deep fibular (deep peroneal) nerve run together along the front of the interosseous membrane. The branches of the superficial fibular nerve emerge through the fascia in this region as well. Contact with either nerve is documented as producing a sharp sensation radiating toward the ankle or the top of the foot; that is the practical reason the texts give a bounded figure rather than an open one, and the reason the point is described as lying two finger-breadths lateral to the tibial crest rather than directly over the bone.

No pregnancy caution and no organ hazard is recorded at this point in the standard references. Local bruising is the event most often noted at leg points. Standard clean-needle practice applies. Acupuncture is carried out only by a qualified, licensed practitioner; this record documents the literature and is not a technique guide.

Source: Sacred Lotus sources & references (existing needling record); Chinese Acupuncture & Moxibustion, p. 155; Deadman & Al-Khafaji, A Manual of Acupuncture, p. 165 (surface and deep anatomy of the anterior compartment of the leg).

What does the name Feng Long mean?

Feng Long translates as "Bountiful Bulge" — feng meaning abundant, plentiful or plump, and long meaning a swelling, a mound or a rise. The plain reading is descriptive: the point sits on the full, rounded bulge of muscle on the outer front of the lower leg, and the name tells a practitioner where to press. A second reading, recorded in the classical literature and repeated in the modern reference texts, takes Feng Long as the name of the thunder deity of Chinese myth — the figure who musters and scatters the clouds. Since phlegm is imagined in Chinese medicine as a turbid cloud that obscures the head and mists the orifices of the Heart, the association between a cloud-scattering thunder god and the body's principal phlegm point is one the tradition has enjoyed for centuries. Both readings are recorded; neither displaces the other.

Why is ST-40 called the phlegm point?

Because from the Ming dynasty onward the acupuncture literature says so, in almost those words. What is worth knowing — and what most summaries leave out — is that the association was built up over a long period rather than being present from the start. A textual study published in Zhongguo Zhen Jiu traced the indications of Feng Long through the Huangdi Neijing, the Huangdi Mingtang Jing and the excavated Tianhui medical bamboo slips, and found that the earliest recorded indications for the point centre on qi rising when it should be descending, not on phlegm as such. Phlegm theory itself was largely constructed in the Sui and Tang periods; physicians of the Song, Jin and Yuan then linked phlegm to the movement of qi, and in Dou Hanqing's acupuncture writings Feng Long is selected for phlegm-damp and phlegm wheezing — still, the study argues, on the basis of counterflow qi rather than of phlegm directly. It is the later verse literature, the Yu Long Ge (Jade Dragon Song) and the Zhen Fang Liu Ji, that puts the point and phlegm together explicitly, after which the formula "Feng Long, the key point for phlegm disorders" settles into place from the Ming dynasty on (PMID 38986599).

Two things follow, and both are useful. The phlegm reputation is genuine, long-established and clinically real — it is what the point is used for. But its deeper mechanism, as the tradition itself originally framed it, is the descending of rebellious qi, which is why ST-40 is recorded for wheezing, vomiting, dizziness and mania as well as for sputum. Understanding it as a descending point that thereby resolves phlegm explains its range better than treating phlegm as an isolated property.

How does ST-40 differ from nearby points?

ST-38 Tiao Kou lies at the same level on the same channel, one finger-breadth medial to ST-40, and is a local and shoulder point rather than a phlegm point — the two are close enough that careful location matters. ST-36 Zu San Li sits higher on the channel and builds qi and blood rather than clearing turbidity; it is ST-40's most common partner precisely because their actions are complementary. SP-09 Yin Ling Quan, on the inner side of the leg, is the point reached for when the pathology is read as damp and water rather than as phlegm — thinner and more diffuse than what ST-40 addresses. And SP-04 Gong Sun is ST-40's structural mirror: the Connecting point of the Spleen as ST-40 is the Connecting point of the Stomach.

Is there research on ST-40?

ST-40 has a real experimental literature, but it is almost entirely laboratory work in animals directed at blood lipids — there is no good clinical trial of ST-40 alone for a phlegm-type complaint in humans, and it would be misleading to present the animal work as if there were.

• A controlled experiment in rats with diet-induced hyperlipidaemia applied electroacupuncture at ST-40 alone and reported reductions in serum total cholesterol, triglycerides and LDL cholesterol, reduced hepatic lipid accumulation, and changes in the AMPK/mTOR signalling pathway and downstream cholesterol-handling proteins; adding an AMPK inhibitor reversed the effect, which is the design feature that makes the result interesting rather than merely descriptive. This is a mechanistic animal study, not evidence of clinical benefit in people (PMID 39401813).
• A further rat study compared electroacupuncture at ST-40 with electroacupuncture at ST-36 on liver lipid handling, keeping the two points distinct rather than pooling them (PMID 40059048).
• A randomised, single-blind controlled trial in 60 patients with Wagner grade 0 diabetic foot compared a specific needling technique at ST-40 with ordinary needling at the same point, and reported an immediate increase in peripheral microcirculatory perfusion measured by laser speckle contrast imaging and a greater reduction in the temperature difference between the two soles, with effects returning to baseline within thirty minutes and no significant adverse effects. It is a small single-session study of an immediate physiological response, not of clinical outcome (PMID 41957887).
• A data-mining analysis of acupoint selection in the treatment of metabolism-associated fatty liver disease documents how often ST-40 is chosen by practitioners in that literature. Studies of this kind describe prescribing habit, not effectiveness (PMID 38649212).
• The historical textual study cited above is a scholarly analysis of the classical record rather than a clinical study, and is the strongest source on this page for what the point has actually been used for and why (PMID 38986599).

The reasonable summary is that ST-40 is being investigated seriously for lipid and metabolic effects, that the animal data are internally consistent, and that none of it yet says anything about whether needling ST-40 helps a person with cough, dizziness or high cholesterol. Its standing rests on the classical and clinical record, not on trial evidence.

Source: Sacred Lotus sources & references; Deadman & Al-Khafaji, A Manual of Acupuncture, p. 165; Chinese Acupuncture & Moxibustion, p. 155; Ling Shu (Spiritual Pivot), Chapter 10; Yu Long Ge and Zhen Fang Liu Ji via PMID 38986599; PubMed PMID 38986599, 39401813, 40059048, 41957887, 38649212 (each verified resolvable and checked for retraction status before citation); cross-referenced against multiple online sources.