Skip over swollen, tender or varicose veins behind the knee.
委中 Weizhong
“Bend Middle” · BL40
Foot Taiyang · 40 of 67 · he-sea, lower-he-sea of the bladder
Where. At the centre of the crease behind the knee, between the two tendons.
For. Low back and spine ache; weak legs.
Press. Knee bent, gentle fingertip pressure, about a minute each leg.
Caution. Skip over swollen, tender or varicose veins behind the knee.
委中，膕中央，為合，委而取之按 · Press with me
Six slow breaths
About a minute. Press as you breathe out, ease as you breathe in.
配 · Pairs with
鄰 · Neighbouring leaves
症 · Often paired with
Where Weizhong Sits Behind the Knee
The dataset locates Weizhong in one measured sentence: at the midpoint of the popliteal crease, between the tendons of biceps femoris and semitendinosus. Unpacked for hands rather than anatomy charts: the popliteal crease is the horizontal skin fold at the back of the knee — the crease that deepens whenever the knee bends — stretched between two prominent cords. The cord on the outside belongs to biceps femoris, the hamstring that wraps around to the outer side of the knee; the cord on the inside belongs to semitendinosus, its partner of the inner border. Weizhong stands halfway along the fold, squarely between the two, arriving as a mirrored pair with one station behind each knee. Notice how economical the definition is: one landmark every body owns and one relationship — the middle of it — with no measuring to perform.
What lies beneath the fingertips here is soft country. Behind the knee the leg opens into a roomy hollow, padded deeply with fat, and through this hollow pass the great vessels and nerves serving the whole lower leg — the corridor, in older terms, between thigh and calf. Everything important lies well below the padding, out of reach of anything fingertip contact can exert, which is part of why the licensed record lists no specific caution for this point. The hollow also shapes the feel of the place: the tissue reads as giving rather than dense, and a light touch takes in everything worth knowing. What the geography asks instead is obedience to the stop signals below — sharp, electric, or radiating sensation never gets pressed through, because a busy nerve pathway runs the neighbourhood.
The wider map shows why this station carries such weight in the tradition. Weizhong belongs to the bladder channel, the longest road in the classical cartography — sixty-seven stations strong, drawn from the inner corner of the eye, sweeping over the head, descending the whole length of the back, crossing the buttock, and running down the back of the thigh to this crease before continuing down the back of the calf toward the little toe. The catalogue anchors the surrounding line to this point: Yinmen (BL37) above is measured on the line connecting Chengfu (BL36) and Weizhong, and the calf stations below are measured from Weizhong downward toward Chengshan. Even the crease’s outer end keeps its own address — Weiyang (BL39), tucked against the medial side of the biceps femoris tendon — so the whole landscape reads outward from the midpoint. A hub like this earns its reputation honestly.
A Self-Palpation Walkthrough
Begin by choosing a position that lets the crease speak. Sitting on the front edge of a chair with the foot flat on the floor bends the knee just enough to deepen the fold; lying face down with a small pillow under the ankles works equally well and keeps the leg fully relaxed. Rest your fingertips on the back of the knee and find the horizontal crease where thigh turns to calf. Trace it from the inner border to the outer, noticing the two structures that bound it — a firm, rounded cord rolling under the fingers toward the outside, and flatter strands gathering toward the inside. Having walked the whole fold, return to its middle: halfway between the cords, right on the crease line, is the address the dataset records.
A few quiet checks settle the placement. Touch feather-light and compare knees: many people notice a faint dull awareness or mild tenderness at the true spot and little sensation a finger-width away, though some feel nothing distinctive at all — absence of sensation is not absence of location. Check the height: the point belongs on the crease itself, neither climbing into the thigh above nor slipping onto the calf below. Check the width: it sits centred between the two cords, not resting on either. If you want confirmation from the wider line, walk upward along the midline of the thigh’s back toward the buttock crease — the road the channel travels — or simply retrace the fold end to end once more and take its true middle slowly.
The classic mistakes are few and worth naming. The first is settling too high into the soft thigh above the fold, where muscle is plentiful and nothing announces the error; keeping the fingertip glued to the crease prevents it. The second is sliding down onto the upper calf, which feels similar under a lazy finger. The third is drifting onto one of the bounding cords themselves — tendons declare themselves as hard ridges, and the point lives in the space between them, not on them. The fourth is pressing hard, hoping force will reveal what patience finds anyway; force teaches the fingers nothing here. Run the search twice, once behind each knee, and trust the crease you can see more than any number you might remember.
Reading the Name: Bend Middle
The characters tell the location twice over. Wei 委 carries the sense of bending and crooking — the way a willow branch droops, the way a joint folds — and by extension of settling and pooling, of things entrusted and gathered low. Zhong 中 simply means middle, the centre of a space. Read together, Weizhong names the centre of the bend: the exact middle of the hollow the body makes when the knee flexes. Few names in the tradition fit their ground so plainly. The point sits precisely where the name says, in the middle of the crease that appears the moment the knee bends, and the old habit of naming places for their work could hardly have found a tidier specimen.
The name also hints at a deeper office. Classical teaching pictures channel qi as water moving through a landscape: it bubbles up at the fingertips and toes, trickles through shallow valleys, swells into streams, and finally gathers at the stations nearest elbow and knee, pouring seaward like rivers reaching the ocean. The stations holding that gathering office are called he-sea points, and Weizhong holds it for the bladder channel. The teaching adds a second layer: each of the six bowel organs keeps a special lower he-sea station on the yang roads of the leg, where its affairs may be consulted, and the bladder organ’s own lower he-sea point is Weizhong itself — while the neighbouring Weiyang performs the same duty for the san jiao. A bend in the river, a doorway for the organ whose name the channel bears: both readings converge on this one spot.
Pinyin renders the name Wěizhōng, and the tones repay character-by-character attention. Wei carries the third tone — the dipping tone that falls and rises again, written with a small hook above the vowel — while zhong carries the first tone, high and level, written with a plain bar. These are the readings dictionaries record: wei, third tone, for the character meaning to bend or entrust; zhong, first tone, for the character meaning middle. (The same hanzi zhong owns a second, fourth-tone reading meaning to strike the mark, as in hitting a target — a different word entirely, not the one used here.) The hanzi pair 委中 stays compact enough to memorise at a glance, and like the gates, valleys, and courtyards scattered along the channel, the metaphor does honest work: it tells you where you are. The name is itself a small set of instructions.
Traditional Indications, Explained
The recorded indications read: pain of the lower back and spine; atrophy and paralysis of the lower limbs; abdominal pain; acute vomiting and diarrhoea; enuresis; difficult urination; and erysipelas. Framed as tradition rather than promise, the first item is the headline act. Generations of students have memorised a short teaching rhyme of the tradition that sends complaints of the lower back to be sought at Weizhong, and the reason is simple geography: the bladder channel descends the entire length of the back and passes directly through this station on its way to the foot. When discomfort settled anywhere along that long road, classical practice consulted stations standing on it — and none stood more conveniently at the road’s midpoint than this one. Low back and spinal pain appearing here needs little further explanation.
The remaining entries divide by territory. Atrophy and paralysis of the lower limbs is the tradition’s phrase for weakness, withering, and unreliable strength in the legs, and the he-sea stations gathered at knee and elbow were the natural consulting rooms for such discussions. Abdominal pain and acute vomiting and diarrhoea reflect the custom of attending to the trunk’s affairs at stations along the leg’s yang roads. Enuresis and difficult urination follow directly from the lower he-sea identity described above: in the traditional frame the bladder organ’s business pooled at this door, so disorders of passing water were brought here. Erysipelas — a hot, sharply bordered redness spreading across the skin — belonged to the family of heat conditions the tradition discussed along the taiyang road; the record preserves the association without describing any technique, and this page follows its example.
It bears repeating plainly: these are the traditional uses recorded in a licensed dataset and classical literature, offered here for cultural and historical understanding. They are not claims that pressing this point treats disease, and nothing in this guide replaces assessment by a qualified clinician. Where modern research touches self-applied pressure at all, reviews suggest effects are modest and context-dependent, and evidence specific to any single point remains thin. Some entries on this list deserve particular care before they earn any self-care routine: acute vomiting and diarrhoea can dehydrate quickly, and changes in passing water deserve proper eyes on them promptly. Hold the tradition lightly, and hold the safety rules firmly.
Self-Care Acupressure at Home
With the point located by the walkthrough above, settle into position: seated on the front edge of a firm chair with the foot flat and the leg heavy, or lying face down with the ankles supported. Curl your index and middle fingers together and rest the pads — never the tips, never an elbow or any tool — on the centre of the crease. Begin with contact alone for a few breaths, letting the tissue learn the touch, then add small, slow circles, allowing the skin to glide over the padding beneath rather than grinding into it. Pressure should register as pleasant dullness or mild warmth, never sharpness. A common home rhythm is one to three minutes per side, once or twice daily, matched where possible to slow exhales so each circle rides the breath out. Swap hands, repeat behind the other knee, and keep the sessions symmetrical.
Quality matters more than duration. Warm your hands first if they run cold, because chilled muscle guards. Choose a quiet corner over a screen and treat the minutes as a pause rather than a task; people who keep a routine usually anchor it to an existing habit — after a shower, before sleep — because consistency, not intensity, is what self-care traditions actually ask for. The backs of the knees also reward a little movement afterward: standing and walking a few unhurried steps lets the whole posterior line lengthen naturally after being attended to, which suits this territory far better than aggressive stretching ever could. What the region asks of self-care, in short, is gentleness, regularity, and a light hand.
Treat the exercise as a small ceremony of attention rather than a treatment session. Across weeks, notice what changes: perhaps the area feels less guarded when touched, perhaps the legs feel easier after your minute of care, perhaps nothing shifts except that you spent ninety seconds attending to the joints that carry you all day. Every one of those outcomes fits the honest scope of self-acupressure. What does not fit is escalation — pressing harder, longer, or deeper to force a result, especially in a hollow that asks for delicacy. When curiosity pulls that way, return to gentleness or simply stop for the day; the crease will still be waiting tomorrow, exactly where the name says it should be.
Cautions and Safe Practice
Weizhong carries a notably quiet record in the licensed data: the dataset lists no specific caution for this point. Geography explains most of that calm. The important structures behind the knee — the vessels and nerves serving the lower leg — lie deeply buried beneath generous fat padding, beyond the reach of surface contact, and unlike certain stations elsewhere there is no thin barrier between skin and anything fragile. But a quiet record is not a license for force. The hollow is a thoroughfare for nerve traffic between thigh and calf, and the tradition’s own etiquette agrees with common sense: sharp, electric, or radiating sensation means stop at once, not press through, and discomfort that worsens means the session is finished for today.
For fingertip acupressure the practical rules are simple. Use finger pads only and keep pressure comfortable throughout; skip the point entirely over broken, bruised, or irritated skin, and over any swollen or tender veins behind the knee; and pause during an acute flare of knee or back trouble. After recent injury to the knee, or after surgery in the region, wait until a clinician has cleared ordinary movement before adding any point practice. Pregnant readers should consult a qualified practitioner before starting a new routine, and anyone living with circulatory disorders, diabetes affecting the limbs, or diagnosed nerve conditions of the legs does well to ask first — not because gentle surface contact is known to harm, but because individual circumstances deserve individual advice.
And the wider rule stands over everything: this page is educational, and acupressure is self-care, not diagnosis or therapy. Several stories in this region belong promptly with a professional rather than with any pressure routine: swelling, warmth, or cramping pain concentrated in one calf; numbness, tingling, or weakness spreading down a leg; a hot, spreading redness of the skin, especially with fever; vomiting or diarrhoea that is severe or will not settle; new changes in bladder control; or low back pain persisting beyond a few weeks without explanation. Seek licensed medical or East Asian medical care as suits the complaint — alongside self-care rather than instead of it. The safest gift Weizhong offers most people is a kinder acquaintance with the quiet hinge that carries them: attended gently, pressed lightly, and treated with the respect its name has earned.
Weizhong, “Bend Middle”, stands at the exact centre of the crease behind the knee, held between the two hamstring cords. Classical practice sent troubled backs to seek this station, and its recorded uses reach further still — into the legs, the abdomen, the water passages, and the skin. This guide walks through finding it by touch and pressing it gently at home.
Self-care limits
Frequently asked
- How do I find Weizhong without knowing anything about cun?
- You barely need measurements at all. The dataset defines the point by a landmark and a relationship: find the horizontal crease behind the knee, notice the firm cord toward the outside and the flatter strands toward the inside, and rest your fingertip at the middle of the fold, between them. If you want a cross-check, the catalogue measures the calf stations from this very point downward, and Yinmen above stands on the straight line joining the buttock crease to this one — the whole road is strung between landmarks, and Weizhong is its midpoint.
- Is pressing Weizhong myself actually safe?
- Gentle fingertip pressure held on the surface is generally reasonable self-care for healthy adults: the licensed record lists no specific caution, because the delicate structures behind the knee lie deeply padded and out of reach of surface contact. Safety here is mostly restraint — light force, pads not tips, healthy skin only, nothing pressed into swollen or tender areas — and immediate respect for sharp, electric, or radiating sensations, which mean stop rather than press harder.
- What did classical practice use Weizhong for?
- The traditional record lists pain of the lower back and spine, atrophy and paralysis of the lower limbs, abdominal pain, acute vomiting and diarrhoea, enuresis, difficult urination, and erysipelas. Low back pain heads the portfolio — a teaching rhyme generations of students memorised sends back complaints to this station — and the urinary entries follow from its role as the bladder organ’s lower he-sea point. Those are traditional frameworks for understanding the body, documented for context — not evidence-backed treatment claims.
- Why does a point behind the knee appear in old discussions of urination and digestion?
- Because of the lower he-sea teaching: classical theory assigned each of the six bowel organs a gathering station on the yang roads of the leg, where its affairs could be consulted without working on the trunk directly. The bladder organ’s gathering station is Weizhong itself, and the neighbouring Weiyang serves the san jiao the same way. Attending to the water passages at a station on the channel bearing the bladder’s name was therefore straightforward traditional reasoning, recorded here for cultural understanding rather than asserted as mechanism or outcome.
- Can acupressure at Weizhong replace seeing a doctor about my back pain?
- No. Self-acupressure is a comfort practice, not a diagnostic tool, and several warning signs in this region deserve prompt assessment: swelling or one-sided pain concentrated in a calf, numbness or weakness travelling down a leg, a spreading hot redness of the skin, severe vomiting or diarrhoea, changes in bladder or bowel control, or back pain persisting beyond a few weeks. Think of the two as different floors of the same building: daily self-care lives downstairs, and clinical medicine keeps the consulting room upstairs that you visit when symptoms persist or frighten you. Neither substitutes for the other.
Sources
- 01WHO Standard Acupuncture Point Locations in the Western Pacific Region (2008), World Health Organization — nomenclature conventions.
- 02A Manual of Acupuncture, Peter Deadman, Mazin Al-Khafaji and Kevin Baker — point-name tradition, he-sea theory, and bladder-channel context.
- 03aijiu-mpvue (MIT License) licensed dataset, entry for BL40 Weizhong — location, point class, actions, and indication record.
Last reviewed
牌記This leaf, for machines
Old books ended with a colophon saying who printed them. Every leaf here carries the same facts as structured data for agents and search, with no layout in the way.
- GET /en/points/bl40/leaf.json
- GET /zh-hant/points/bl40/leaf.json
- GET /zh-cn/points/bl40/leaf.json
- /llms.txt — the index of every leaf
- JSON-LD in the page: MedicalWebPage, MedicalEntity and FAQPage
{
"id": "BL40",
"name": {
"en": "Weizhong",
"gloss": "Bend Middle",
"zh-Hant": "委中",
"zh-Hans": "委中"
},
"channel": {
"id": "BL",
"order": 40,
"of": 67
},
"location": {
"text": "At the centre of the crease behind the knee, between the two tendons."
},
"for": [
"low back and spine ache",
"weak legs"
],
"press": {
"text": "Knee bent, gentle fingertip pressure, about a minute each leg.",
"seconds": 60,
"sides": "both"
},
"cautions": [
"Skip over swollen, tender or varicose veins behind the knee."
],
"source": "Lingshu, chapter 2",
"url": "https://acupoints.com/en/points/bl40",
"lastReviewed": "2026-08-24"
}