A nerve runs beside this tendon: press gently, and ease off if it tingles.
浮郄 Fuxi
“The Floating Cleft” · BL38
Foot Taiyang · 38 of 67
Where. One thumb-width above the outer end of the knee crease, just inside the tendon at the outer back of the knee.
For. Numb, aching thigh and back of the knee; cramps.
Press. Sit with the knee bent and press with a fingertip, about a minute each leg.
Caution. A nerve runs beside this tendon: press gently, and ease off if it tingles.
浮郤，在委陽上一寸，屈膝得之按 · Press with me
Six slow breaths
About a minute. Press as you breathe out, ease as you breathe in.
鄰 · Neighbouring leaves
Where Fuxi Sits Behind the Knee
The dataset locates Fuxi in a single breath: at the lateral end of the popliteal crease, one cun above Weiyang (BL39), on the medial side of the biceps femoris tendon. Unpacked for hands rather than rulers: the popliteal crease is the skin fold at the very back of the knee, the line the leg folds along whenever the knee bends. Its lateral end is where the fold thins away toward the outer edge of the leg, and that corner is marked by Weiyang, a bladder-channel station sitting right on it. One cun above that corner — roughly one thumb-width up the thigh — lies Fuxi. A cun, as always in this cartography, is a proportional unit taken from the person being examined rather than a fixed ruler length, so the distance scales with the body: long-legged adults carry their cun farther than slight teenagers do.
What rests under the fingertip here is muscle in transition. The biceps femoris is the outermost of the hamstrings, the group of muscles running down the back of the thigh, and near the knee its belly narrows into a firm cord — the tendon — that continues toward the small bone at the outer side of the knee. Medial side of that tendon means the flank facing the middle of the back of the knee, not the outer thigh: the point hugs the tendon on its inner face, where muscle softens toward the fat-padded hollow below. That hollow, the popliteal fossa, is the diamond-shaped space behind the knee through which vessels and nerves travel between thigh and lower leg — which is exactly why every suggestion on this page keeps pressure superficial and aimed at muscle, never plunged into the depths of the hollow.
Neighbors fix the address on the map. At the exact midpoint of the crease stands Weizhong (BL40), the best-known station of the whole knee region, seated between the two tendon groups; at the lateral end sits Weiyang (BL39); and one cun above Weiyang hovers Fuxi. All three belong to the bladder meridian, the longest pathway in the traditional cartography — sixty-seven stations strong, drawn from the inner corner of the eye, sweeping over the head, descending the whole back, crossing the buttock and the back of the thigh, and ending at the little toe. Five-phase teaching assigns the channel to water, tending the body’s surface flows alongside the kidney’s deep reserves. Notably, the licensed record attaches no special point-class label to this station — it stands as an ordinary stop on the route, named for its place in the landscape rather than for a rank.
A Self-Palpation Walkthrough
Choose a posture that lets the back of the knee soften: sitting with the foot resting flat on a low stool, lying face down with a pillow under the ankle, or standing with the heel propped and the knee barely bent. Begin by letting the knee flex a little so the crease appears, and trace it outward until the fold fades at the outer edge of the leg — that fading corner is the territory of Weiyang. Rest your fingertip there, then glide it straight up the back of the thigh about one thumb-width. Under the pad you will feel the firm cord of the biceps femoris tendon; settle your fingertip just on its inner side, the side facing the middle of the knee. Repeat the whole search on the other leg so both sides receive the same careful attention.
A few quiet confirmations help before any pressing begins. Touch feather-light and compare sides: most people notice a broad, dull awareness at the true spot and little sensation a finger-width away. Flex the knee gently against nothing at all — the tendon cord tightens and slides under the finger, and you can check that your fingertip sits beside it rather than on top of it. Audit the vertical too: if what you feel is the crease fold itself, you have stayed at Weiyang and simply need to climb a thumb-width higher; if you are already up amid the soft mid-thigh muscle with no tendon nearby, you have wandered into Yinmen’s (BL37) neighborhood and should come back down.
The classic mistakes are worth naming so they can be dodged. The first is stopping on the crease itself — comfortable, plausible, and one station low. The second is sliding outward past the tendon onto the bare outer thigh, where the landmarks thin out. The third is drifting inward toward the soft centre of the hollow behind the knee, which this page treats as territory to skirt, never to press. And the fourth is pressing harder, hoping force will clarify what patience would have found anyway; force teaches the fingers nothing here. Lighten the touch, slow the search, and let the cord and the corner announce themselves.
Reading the Name: the Floating Cleft
The first character tells half the story openly. Fu 浮 means floating — the image of something resting buoyant on water, riding high rather than sunk. Commentators have connected the floating image with the point’s situation: it hovers a clear step above the busy crease below, among tissue that feels looser and more mobile than the taut structures gathered at the knee joint, and a fingertip resting there has the sense of touching something adrift just beneath the surface. Read this way, the name sketches the address before the map does: the cleft that floats above the crossings of the knee.
The second character carries the older, rarer weight. Xi 郄 is an ancient word for a narrow gap or crevice, kin to the commoner character 隙, and in the naming of points it marks spaces between muscle, tendon, and bone — the kinds of seams practitioners met with a fingertip long before anatomy books drew them. The same character lends its name to a separate classical family of cleft points elsewhere on the body; the licensed record attaches no such label to this station, so take the resemblance as shared vocabulary, not classification. Together the pair reads as the floating cleft — a gap beside a tendon, sought where things ride light.
Pinyin renders the name Fúxì, and the tone marks repay checking against a dictionary rather than memory. The first syllable fu carries the rising second tone — fú — the voice lifting as the syllable ends, exactly as dictionaries give for 浮. The second syllable xi carries the falling fourth tone — xì — delivered with a firm downward step; dictionaries give precisely this reading for 郄 in point names, reserving its other reading qiè for surname usage far from medicine. The hanzi pair 浮郄 stays short enough to memorise at a glance. Like the gates, valleys, courtyards, and storehouses scattered along the channel, the metaphor does honest work: it marks a working seam in the landscape of the knee, not scenery.
Traditional Indications, Explained
The recorded indications read: pain and numbness of the thigh and popliteal fossa, constipation, weak legs and knees, and cramps. Framed as tradition rather than promise, most of the list gathers naturally around the locality. The channel passes straight down the back of the thigh through this very stretch, so ache, deadened feeling, or heaviness anywhere between thigh and hollow was traditionally consulted along the road itself. Weak legs and knees echoes the classical language of limbs gone unreliable — strength that will not answer, stairs that feel uncertain. Cramps is the old records’ plain word for muscle seizing suddenly into knots, the familiar complaint of calves and hamstrings that tighten without invitation.
Constipation looks like the stranger on the list, and honesty serves better than cleverness here. Traditional logic built several bridges, and the gentlest is geographic: the channel descends past the sacrum, the territory where classical practice located the body’s lower drainage works, and stations along its course were consulted when bowels stalled. The neighborhood supports the pattern — Chengfu (BL36), higher on the same stretch, carries parallel entries for constipation and related complaints in the same licensed dataset. Reaching below an ailing region for a point on the road that passes through it runs all through classical practice; this entry reads as one instance of that habit rather than a special secret of this station.
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. 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 with the foot on a low stool, or lying face down with the ankle supported and the knee soft. Curl your fingers and rest the pads — never the tips, and never an elbow or any tool — on the spot beside the tendon cord. Begin with contact alone for a few breaths, then add small, slow circles, letting skin glide over the muscle rather than grinding against the tendon. Pressure should register as pleasant dullness or mild warmth spreading into the tired tissue, never sharpness. A common home rhythm is one to three minutes per side, once or twice daily, matched where possible to slow exhales, with both legs kept 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 practice as a pause rather than a task; people who keep it up often anchor it to an existing habit — after the evening walk, before bed — because consistency, not intensity, is what self-care traditions actually ask for. Pairing helps too: a minute of gentle pressure followed by easy movement, such as standing and bending the knee softly a few times, or lying down and drawing the knees toward the chest, suits the back of the thigh far better than aggressive stretching of cold muscle.
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 after long days on your feet, perhaps the pause becomes the evening’s quietest minute, perhaps nothing shifts except that you spend two minutes attending to your own legs. 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. When curiosity pulls that way, return to gentleness or simply stop for the day; the cleft will still be there tomorrow, exactly where the tendon and the corner said it would be.
Cautions and Safe Practice
This point carries a notably quiet record in the licensed data: the dataset lists no specific caution for Fuxi. Geography explains much of that calm. Beneath the skin lies thick, well-covered muscle — the meaty convergence of the hamstrings — with no delicate structure within reach of anything surface contact could exert. But calm deserves a footnote: just below, the popliteal hollow carries vessels and nerves traveling between thigh and lower leg, so home care keeps to the muscle beside the tendon and skirts the deep centre of the hollow entirely. A quiet record is permission for gentleness, not for force.
For fingertip acupressure the practical rules are simple. Use finger pads only, and keep pressure light enough to stay pleasant throughout; aim the attention at the muscular ridge beside the tendon rather than downward into the knee hollow. Skip the point entirely over broken, bruised, or irritated skin, over visible veins that ache, during an acute flare of knee or thigh trouble, and for a stretch after any injury or surgery in the region until ordinary movement has been cleared by a clinician. Sharp, electric, or radiating sensation means stop at once and do not try again that day. Pregnant readers should consult a qualified practitioner before adding any new point practice, and anyone managing circulation problems or diagnosed nerve conditions of the legs does well to ask first too.
And the wider rule stands over everything: this page is educational, and acupressure is self-care, not diagnosis or therapy. Some stories behind the knee need prompt professional attention rather than any pressure routine: numbness, tingling, or weakness that persists or spreads, one-sided swelling, warmth, or colour change in calf or knee, pain following a fall or accident, or symptoms persisting without explanation beyond a few weeks. Seek licensed medical or East Asian medical care as suits the complaint — promptly, alongside self-care rather than instead of it. The safest gift Fuxi offers most people is a kinder acquaintance with the back of their own knee: attended regularly, pressed gently, and never rushed.
Fuxi, the Floating Cleft, waits just above the outer corner of the crease behind the knee — one cun above Weiyang, resting against the biceps femoris tendon. Classical practice reached for it when thighs ached or went numb, legs and knees weakened, or muscles cramped. This guide walks through finding it by touch and pressing it gently at home.
Self-care limits
Frequently asked
- How do I find Fuxi without knowing anything about cun?
- Use the corner of the crease as your whole map. Let the knee bend softly so the crease appears, trace it outward to where the fold fades at the outer edge of the leg, and rest a fingertip there — that corner is Weiyang’s territory. Then glide one thumb-width straight up the back of the thigh and settle beside the firm tendon cord, on the side facing the middle of the knee. The cun measurement simply encodes that same thumb-width in proportional language.
- Is pressing Fuxi 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 for this point, because thick muscle lies beneath and nothing fragile sits within reach of surface contact. The one refinement this page adds is direction — press the muscle beside the tendon rather than diving into the soft centre of the hollow behind the knee, where vessels and nerves pass. Respect the stop signals: sharp or radiating sensation means finish immediately.
- What did classical practice use Fuxi for?
- The traditional record lists pain and numbness of the thigh and popliteal fossa, weak legs and knees, cramps, and constipation — a portfolio centred on the back of the leg, with one bowel entry riding along by the tradition’s distal-point logic. Those are traditional frameworks for understanding the body, documented for context — not evidence-backed treatment claims.
- Why would a point behind the knee appear in old lists about constipation?
- Because classical practice thought along channels rather than organs alone. The bladder channel descends past the sacrum — the region tradition associated with the body’s drainage works — and continues down the back of the thigh through Fuxi’s neighborhood, so stations on that road were consulted when bowels stalled. Neighboring Chengfu carries parallel bowel entries in the same dataset. It is traditional reasoning, recorded for understanding — not a modern treatment claim.
- How is Fuxi different from Weiyang and Weizhong next door?
- They are three addresses along one corner. Weizhong (BL40) sits at the exact midpoint of the crease, Weiyang (BL39) at its lateral end, and Fuxi one cun above Weiyang, on the medial side of the tendon — hovering just off the corner rather than standing on it. Their recorded portfolios differ accordingly: Weizhong and Weiyang lean toward back pain and urinary complaints, while Fuxi stays local — thigh, hollow, legs, cramps. Same stretch of road, different doors.
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 and bladder-channel context.
- 03aijiu-mpvue (MIT License) licensed dataset, entry for BL38 Fuxi — location, 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/bl38/leaf.json
- GET /zh-hant/points/bl38/leaf.json
- GET /zh-cn/points/bl38/leaf.json
- /llms.txt — the index of every leaf
- JSON-LD in the page: MedicalWebPage, MedicalEntity and FAQPage
{
"id": "BL38",
"name": {
"en": "Fuxi",
"gloss": "The Floating Cleft",
"zh-Hant": "浮郄",
"zh-Hans": "浮郄"
},
"channel": {
"id": "BL",
"order": 38,
"of": 67
},
"location": {
"text": "One thumb-width above the outer end of the knee crease, just inside the tendon at the outer back of the knee."
},
"for": [
"numb",
"aching thigh and back of the knee",
"cramps"
],
"press": {
"text": "Sit with the knee bent and press with a fingertip, about a minute each leg.",
"seconds": 60,
"sides": "both"
},
"cautions": [
"A nerve runs beside this tendon: press gently, and ease off if it tingles."
],
"source": "Zhenjiu Jiayi Jing, book 3",
"url": "https://acupoints.com/en/points/bl38",
"lastReviewed": "2026-08-24"
}