A powerful point on the back of the thigh, Yinmen (BL-37) opens and moves Qi and Blood (Xue) along the Bladder Meridian (BL), making it one of the go-to points for deep, stubborn pain running down the lower back, buttock and leg — the classic pathway of sciatica.
Contraindications
A straightforward point in a fleshy, well-muscled area. No special contraindications; keep to the recommended depth and use clean technique.
Name & story
殷门 Yinmen carries a name with real weight: 殷 (yīn) means 'abundant', 'rich', or 'deep and full', and 门 (mén) means 'gate' or 'door'. So the point is the Gate of Abundance — a doorway into the deep, fleshy, powerful region of the posterior thigh. It sits in one of the most muscular parts of the leg, where the channel runs through thick, rich tissue. The name also hints at the point's nature: it opens a gate for Qi and Blood (Xue) that have become stuck or obstructed in this deep, dense territory.
Point family & character
Yinmen (BL-37) belongs to the Bladder Meridian (BL), the longest channel in the body, which sweeps down the entire back of the leg from the buttock to the little toe. The point has no special category such as He-Sea or Xi Cleft — it is a straightforward point of the channel, valued for its precise location along the posterior thigh and its strong local and regional action.
Five-element dynamics
The Bladder Meridian (BL) belongs to the Water element and is the great Yang channel of the back and lower limbs. When Cold, Dampness or Blood Stasis settles into the deep muscles and sinews of the posterior thigh, the channel's flow is blocked and pain results. Yinmen (BL-37) sits right in that territory, acting as a gate that can be opened to restore the smooth, abundant flow of Qi and Blood (Xue) through the leg.
Location
On the back of the thigh, on the line joining BL-36 (Chengfu, at the centre of the gluteal fold) and BL-40 (Weizhong, at the centre of the popliteal fold). Yinmen (BL-37) lies 6 Cun below BL-36, roughly in the middle of the posterior thigh, slightly closer to the upper end of that line.
Anatomy & fascia
The point lies in the posterior compartment of the thigh, between the biceps femoris and semitendinosus muscles — the great hamstring group. The sciatic nerve runs in this region, which explains the point's powerful reach into sciatica-type pain.
Needling
The needle is inserted perpendicularly (straight in). A strong, spreading sensation — often described as an electric or radiating feeling down the leg — is frequently obtained and is considered a good sign for sciatica and posterior leg pain.
Safe depth
Safe depth — 1–2 Cun.
Moxa, cupping & Tui Na
Warming methods such as Moxa or warm needle technique are well suited when the pain is made worse by cold and damp, or when there is a sense of heaviness and stiffness. Cupping over the posterior thigh is also commonly used to move Blood Stasis and relieve deep muscle tightness. Firm massage or Tui Na along the hamstring line can complement needling for home self-care.
Functions
Removes obstruction from the Bladder Meridian (BL) and opens the channel in the posterior thigh. Moves Qi and Blood (Xue) and alleviates pain. Relaxes the sinews and benefits the lower back and leg.
Indications
Lower back pain radiating down the posterior thigh and leg (sciatica); pain, stiffness or heaviness in the back of the thigh; difficulty straightening or bending the leg; weakness or numbness running down the leg; contraction or spasm of the hamstring muscles.
Point combinations
With BL-40 (Weizhong) and BL-36 (Chengfu) — to clear the entire posterior leg line and address sciatica from root to branch. With BL-23 (Shenshu) and BL-25 (Dachangshu) — to reinforce the treatment of lower back pain with leg radiation. With GB-34 (Yanglingquan) — to relax the sinews and ease pain along the leg.
Clinical spotlight
Yinmen (BL-37) is one of the most direct and effective points for sciatica — pain that shoots down the back of the thigh along the Bladder Meridian (BL) pathway. Its location right over the hamstring group and the sciatic nerve means that a well-placed needle here can produce an immediate, radiating sensation that reaches far down the leg. For practitioners, it is a reliable local point that complements the distal classics BL-40 and BL-60 when the pain is clearly localised in the posterior thigh.
The golden tip
For aching or tight hamstrings and pain running down the back of the thigh, ask a partner to apply firm, sustained thumb pressure to the midpoint of the back of the thigh — roughly halfway between the buttock fold and the back of the knee. Hold for 1–2 minutes on each side. Warmth over the area — a warm pad or gentle heat pack — also helps when the pain feels worse in cold or damp weather. Gentle hamstring stretching between sessions supports recovery.
For education only — not medical advice. Consult a qualified practitioner.