ST40 (Fenglong / Abundant Bulge) Acupuncture Point Guide

Practitioner Guide from The Acupuncture Supply Co.
Professional acupuncture supplies and practical clinical resources for qualified practitioners in Ireland and across Europe.

ST40, known as Fenglong (“Abundant Bulge”), is the Luo-Connecting point of the Stomach channel. It lies on the anterolateral lower leg and is traditionally regarded as a principal point for transforming Phlegm, resolving Dampness, harmonising the Stomach and calming the Shen.

Location requires proportional measurement combined with palpation of the tibialis anterior border. Because neurovascular structures lie within the anterior compartment and the superficial anatomy varies, technique must be adapted to the individual. This article is a professional reference for trained practitioners, not a self-needling guide.

ST40 Fenglong quick reference

Point name	ST40 — Fenglong (“Abundant Bulge”)
Channel	Stomach channel of Foot Yangming
Classification	Luo-Connecting point of the Stomach channel
Region	Anterolateral lower leg
Laterality	Bilateral
Core landmark	8 B-cun superior to the prominence of the lateral malleolus, at the lateral border of tibialis anterior

Location of ST40 Fenglong

The WHO standard locates ST40 on the anterolateral aspect of the leg, at the lateral border of tibialis anterior, 8 B-cun superior to the prominence of the lateral malleolus.

How to locate ST40

1. Position the patient supine with the lower leg supported and the ankle in a neutral position.
2. Identify the prominence of the lateral malleolus and the relevant proportional lower-leg span.
3. Measure 8 B-cun superiorly using the patient’s body-proportional method.
4. Ask the patient to dorsiflex gently if needed to make tibialis anterior easier to identify.
5. Locate the point at the lateral border of tibialis anterior and reassess the tissue with the muscle relaxed.

ST40 is often described as level with ST38, but it lies farther lateral. Do not rely on a generic “mid-calf” visual estimate: proportional measurement and the lateral border of tibialis anterior are both required.

Traditional functions of ST40

• Transforms Phlegm and resolves Dampness.
• Harmonises the Stomach and redirects rebellious Qi.
• Calms the Shen and clears Phlegm affecting the sensory orifices in traditional theory.
• Activates the channel and benefits the chest, throat and lower leg.
• Connects the Stomach and Spleen channels through its Luo-Connecting classification.

“Phlegm” is a traditional diagnostic concept that may include, but is not limited to, respiratory mucus. These traditional descriptions are not claims that ST40 has been proven to cure respiratory, digestive, metabolic or mental-health conditions.

Traditional clinical applications

ST40 may be considered within an individualised treatment plan where the pattern includes:

• Traditional Phlegm or Dampness presentations.
• Chest oppression, cough or throat symptoms after appropriate medical assessment.
• Nausea, epigastric discomfort or rebellious Stomach Qi in a relevant pattern.
• Dizziness, heaviness or clouded sensation attributed to Phlegm within traditional diagnosis.
• Agitation, poor sleep or emotional disturbance where Phlegm obstructing the Shen is diagnosed.
• Local anterolateral lower-leg discomfort along the channel.

Acute breathlessness, chest pain, coughing blood, sudden confusion, severe headache, fainting, new neurological signs or a mental-health crisis requires urgent conventional assessment.

Common point combinations

• ST40 + SP9: traditionally selected to address Phlegm and Dampness.
• ST40 + CV12: considered where Phlegm arises with impaired middle-Jiao transformation.
• ST40 + ST36: used to harmonise the Stomach and support Qi while addressing Phlegm.
• ST40 + PC6: considered for chest, nausea or Shen presentations within an appropriate pattern.
• ST40 + CV17: traditionally selected where chest Qi and Phlegm are both relevant.
• ST40 + Yintang: sometimes combined when agitation, sleep disturbance or clouded sensation is present.

These are traditional examples rather than fixed prescriptions. Point selection should follow the complete diagnosis, medical history and treatment goals.

Anatomy and practitioner notes

• The point lies near the lateral border of tibialis anterior and the anterior intermuscular septal region.
• Branches of the superficial fibular nerve may be encountered superficially; the deep fibular nerve and anterior tibial vessels occupy deeper anterior-compartment planes.
• Body habitus, muscle development and previous compartment injury can change apparent depth and resistance.
• Ask about fracture, fasciotomy, chronic exertional compartment symptoms, peripheral neuropathy, vascular disease and lower-leg surgery.
• Inspect for varicosities, oedema, infection, bruising, altered sensation or poorly healed tissue.

Needling and essential safety

Needling direction, depth and stimulation must be individualised. This guide deliberately avoids a universal depth because leg anatomy and tissue thickness vary.

• Confirm the border of tibialis anterior with the muscle relaxed before insertion.
• Avoid visible or palpable vessels and do not use forceful deep manipulation.
• Stop and reassess if the patient experiences sharp, electric, burning or strongly radiating sensation.
• Avoid needling through infection, ulceration, significant oedema, bruising or compromised tissue.
• Use sterile, single-use needles and appropriate clean-field and sharps-disposal procedures.

Moxibustion

Moxibustion may be considered in selected Cold-Phlegm or deficiency patterns. Protect the skin, supervise continuously and avoid heat where sensation or circulation is impaired, tissue is inflamed or the clinical pattern makes warming unsuitable.

Research note

ST40 is included in research on metabolic, neurological, respiratory and mental-health presentations, commonly within multi-point protocols. Heterogeneous diagnoses, techniques and outcomes make it inappropriate to attribute a protocol’s findings to ST40 alone. Evidence should be evaluated condition by condition.

Frequently asked questions

Where is ST40 located?

It is 8 B-cun above the prominence of the lateral malleolus at the lateral border of tibialis anterior.

What does the traditional term “Phlegm” mean here?

It is a broad traditional pattern concept and is not synonymous only with visible respiratory mucus.

Why is ST40 called a Luo-Connecting point?

Traditional channel theory identifies it as the Luo point of the Stomach channel, with a connecting relationship to the Spleen channel.

Can this article be used for self-needling?

No. Safe acupuncture requires professional training, anatomical assessment and sterile technique.

Continue exploring Project Lotus

Visit our Acupuncture Point Guides, or read our ST36 Zusanli Guide, SP6 Sanyinjiao Guide, SP9 Yinlingquan Guide and CV17 Shanzhong Guide.

Practitioners can also browse our professional acupuncture needles, Complete Moxa Guide and professional moxa range.

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Professional disclaimer: This article is provided for qualified acupuncture and healthcare practitioners for general educational purposes. Traditional actions describe established acupuncture theory and are not claims of proven clinical efficacy. It is not medical advice, does not replace accredited training and should not be used as a universal treatment protocol. Practitioners remain responsible for assessment, consent, safe technique, infection control, record keeping, referral and compliance with professional and legal obligations.

Reference standards and safety reading:
World Health Organization. WHO Standard Acupuncture Point Locations in the Western Pacific Region.
World Health Organization. Guidelines on Basic Training and Safety in Acupuncture.
World Health Organization. WHO Benchmarks for the Practice of Acupuncture.