ST-31 (Bi Guan) Thigh Joint

What does ST-31 Bi Guan do?

ST-31 activates the channel and alleviates pain, and it dispels wind-damp — the anterior thigh’s local action, and it is the highest point of that run.

• Activates the channel and alleviates pain
• Dispels wind-damp — the classical account of aching, cold, weather-sensitive limbs

Three thigh points, one action record. ST-31, ST-32 Fu Tu and ST-33 Yin Shi all carry exactly these two actions in the same words. ST-31 is the topmost, near the hip, and its indications lean toward the thigh and hip where its neighbours’ lean toward the knee — but the recorded function of all three is uniform, and this library says so rather than inventing distinctions.

Its name marks the hip as a hinge. “Bi Guan” means Thigh Joint or Thigh Gate — bi the thigh, guan a gate, hinge or joint. The point sits near the hip joint, where the thigh moves on the pelvis, and the name reads as the gateway of the thigh. Guan is shared with ST-22 Guan Men and P-06 Nei Guan.

Source: Sacred Lotus sources & references (channel, action, location and translation records; the ST-22, ST-32 and ST-33 action records compared word for word against our own data), cross-referenced against multiple online sources.

What is ST-31 Bi Guan used for?

ST-31 is used for pain in the thigh, and for wasting, weakness, numbness and impaired movement of the leg. Our own indication record is reproduced here in full.

• Pain in the thigh
• Muscular atrophy of the lower extremities
• Motor impairment of the lower extremities
• Numbness and pain of the lower extremities

The whole list is the leg, and thigh pain is the local entry. ST-31 is a regional point for the front of the thigh and the leg below it — pain, wasting, weakness, numbness. It records no organ action and no systemic indication; where a record is this focused, this library reports it as focused.

An honest note. Leg pain with weakness or numbness requires medical assessment, and progressive weakness or visible wasting of the leg needs prompt assessment — it can indicate nerve-root compression at the back or a problem in the spinal cord. Sudden leg weakness is a medical emergency. This record documents classical use for musculoskeletal thigh and leg complaints and should not delay assessment of anything else.

How it is combined. With ST-32 Fu Tu and ST-33 Yin Shi below on the thigh line. With GB-30 Huan Tiao in the buttock — the classical point for the leg — and GB-31 Feng Shi on the outer thigh. With ST-36 Zu San Li below the knee. All held here.

Source: Sacred Lotus sources & references (indication record; the GB-30, GB-31, ST-32, ST-33 and ST-36 records queried from our own data), cross-referenced against multiple online sources.

Where is ST-31 Bi Guan located?

ST-31 is on the upper front of the thigh, just to the outer side of the sartorius muscle, near the hip.

• Just lateral to the sartorius muscle, in a depression at the upper thigh
• At the junction of a vertical line down from the anterior superior iliac spine and the level of the lower border of the pubic symphysis
• ST-32 Fu Tu lies below on the thigh

Sartorius is the landmark, and it is a good one to know. It is the longest muscle in the body, running as a narrow strap from the front point of the hip bone diagonally across the thigh to the inner side of the knee. It stands out when the hip is flexed and turned out — the “tailor’s posture” the muscle is named for — and ST-31 sits just to its outer side near its origin. Locating the point by a muscle that becomes visible on movement is more reliable than a measurement, the same principle our ST-05 record uses with the masseter and SJ-13 with the deltoid.

A practical note. The upper thigh near the groin is a private region of the body, and treatment here calls for the same standards of consent, draping and professional conduct that apply anywhere in that area.

On the name. “Bi Guan” — Thigh Joint, marking the hip as the hinge of the thigh.

Source: Sacred Lotus sources & references (location and translation records, retained unchanged; the ST-05, ST-32 and SJ-13 records queried from our own data).

• A Manual of Acupuncture (p. 154): On the upper thigh, in a depression just lateral to the sartorius muscle, at the junction of a vertical line drawn downward from the anterior superior iliac spine, and a horizontal line drawn level with the lower border of the pubic symphysis.
• Chinese Acupuncture and Moxibustion (p. 153): On the anterior side of the thigh and on the line connecting the anterosuperior iliac spine and the superolateral corner of the patella, on the level of the perineum when the thigh is flexed in the depression lateral to the sartorius muscle.

How is ST-31 Bi Guan needled?

Our own record states perpendicular insertion of 1.0–1.5 inches, with moxibustion applicable — a deep recorded range, matching the thick upper thigh. What follows is a neutral record of what the reference literature documents. It is not instruction, and this page does not teach technique.

• Angle and depth as recorded: perpendicular, 1.0–1.5 inches — matching ST-32 below it, and among the deeper recorded ranges in this library, reflecting the bulk of the quadriceps.
• Moxibustion: recorded as applicable.
• Regional anatomy: the point lies lateral to sartorius over rectus femoris and the tensor fasciae latae; the lateral femoral cutaneous nerve emerges near the anterior superior iliac spine in this region; the femoral neurovascular bundle runs more medially, in the femoral triangle, away from this point; the femur lies deep.

Hazard, stated proportionately. No body cavity, no pleura, no organ. The femoral artery, vein and nerve run medial to this point, in the femoral triangle nearer the midline of the thigh — our SP-12 Chong Men record carries an explicit femoral-artery caution because that point is in the triangle at the groin crease; ST-31 is lateral to it and carries none, and this page does not import it. The lateral position over muscle is what keeps a deep needle clear of the great vessels.

What is not claimed. No study measuring a safe depth at ST-31 could be located, and none is borrowed. Neither measured-depth study this library uses reaches the leg. No case report naming ST-31 was located.

Source: Sacred Lotus sources & references (needling record, retained unchanged, and the ST-32 depth compared; the SP-12 femoral-artery caution queried from our own data and attributed to that point), cross-referenced against multiple online sources; regional anatomy from standard anatomical description.

Is there research on ST-31, and what should a reader know?

No trial isolates ST-31. Where the point appears it is one component of a leg, hip or post-stroke rehabilitation protocol, and a study that includes a point in a protocol is not evidence about that point.

What this page can state with confidence. ST-31 is the highest of the three anterior-thigh points, sharing its action record word for word with ST-32 and ST-33. It is located by sartorius, the longest muscle in the body, which becomes visible on movement — a landmark more reliable than a measurement. Its indications are entirely the thigh and leg. And its deep recorded range, 1.0–1.5 inches, reflects the thick quadriceps, not a hazard: the femoral vessels run medial to it, and the caution that names them belongs to SP-12 at the groin, not here.

A note on searching for it. “ST 31”, “S 31” and “Biguan” searches return protocol trials and a large volume of unrelated material — “Biguan” matches ordinary vocabulary and, in English, an unrelated word. Any claim attached to this point should be checked against what a study actually used.

Source: Sacred Lotus sources & references (action, indication, location and needling records; the ST-32 and ST-33 records compared and the SP-12 caution attributed to that point, against our own data).