Use this acupoint page, BL40 Weizhong: Back-of-Knee Point, Back Relationship, and Safety, when the reader wants this exact point task: Understand BL40 Weizhong before comparing back, knee, Bladder meridian, desk routine, or printable-card pages.
point locator
BL40 Weizhong: Back-of-Knee Point, Back Relationship, and Safety
Understand BL40 Weizhong before comparing back, knee, Bladder meridian, desk routine, or printable-card pages.
Content checked 2026-01-08Point-specific diagramEducation only
Quick Answer
BL40 Weizhong, often remembered as Middle of the Crook, is a Bladder meridian point at the back of the knee. It appears in back-related traditional maps, but the back of the knee is a sensitive area. Swelling, varicose veins, clot concern, knee injury, numbness, severe pain, or unexplained leg symptoms should keep the page read-only.
Safety Decision
Stop before pressure if the body area is injured, the symptom is severe or unusual, or qualified care should come first.
Continue only as a short, comfortable, education-only routine after reading the locator and stop signs.
BL40 WeizhongBefore You Try This
This BL40 page is educational and not medical advice. It cannot assess knee pain, leg swelling, vascular concerns, back pain, injury, numbness, or whether pressure is suitable.
Ask qualified care for leg swelling, varicose-vein concerns, clot concerns, knee injury, severe pain, numbness, weakness, unexplained symptoms, persistent back or leg symptoms, pregnancy, medication questions, children, or chronic illness.
reader path
Is This the Right Page to Read Now?
This acupoint page fails if the Middle of the Crook on the back of knee in the Bladder family locator becomes a treatment shortcut, a stronger-pressure target, or a replacement for the named safety stop signs.
Check knee and leg safety first, then compare BL23, BL60, desk routine, or Safety. Then choose read-only, one brief comfortable contact, a printable card, or a safety stop.
Diagram Notes
The marker highlights BL40 Weizhong, Middle of the Crook, on a back of knee locator view; its landmark cue is "At the back of the knee crease, in a sensitive soft-tissue area." Use it with the safety cues rather than treating the marker as clinical precision.
Locator overlay for BL40 Weizhong, Middle of the Crook, placed on CC BY 4.0 Servier Medical Art human anatomy base images and paired with a regional landmark view.
How to read the BL40 locator
- Start with the broad area: back of knee.
- Compare the written landmark: At the back of the knee crease, in a sensitive soft-tissue area.
- Use the marker as orientation, then let comfort and the avoid varicose veins, swelling, or clot concerns caution decide whether to stop.
The Middle of the Crook locator uses a licensed educational anatomy base for the back of knee; it is not a clinical locator or personal safety clearance.
Why This Page Gets Extra Attention
Reader Scenario
A reader arrives at BL40 after seeing a short chart and needs to verify the Middle of the Crook landmark on the back of knee before doing anything physical.
Common Misread
Do not use BL40 as a leg and back tradition references shortcut; the locator and caution still decide whether this stays reading-only.
Editorial Call
Middle of the Crook earns its length only when it separates back of knee touch, landmark confidence, leg and back tradition references context, and the reason to stop.
Best Next Choice
Choose whether Middle of the Crook should stay read-only, allow one brief comfortable back of knee contact, move to the printable card, or open a safety page.
Use the Middle of the Crook locator as a neighborhood check for the back of knee; the written landmark still outranks the marker.
BL40 Weizhong and the back-of-knee image
BL40 is the standard code for Weizhong, often remembered as Middle of the Crook. The image points to the crease at the back of the knee. That location is the reason the page needs leg and knee caution before any back-related point relationship is considered.
Back-of-knee tissue is not a casual pressure area
The back of the knee is not a place to press through swelling, tenderness, varicose-vein concern, clot concern, injury, numbness, severe pain, or unexplained leg symptoms. Those contexts make the page educational only.
Why BL40 appears in back conversations
BL40 appears in traditional back-related maps because the Bladder meridian links the back body and lower limb. This site can explain that map. It cannot turn a knee-crease point into an answer for back pain or leg symptoms.
How BL40 relates to BL23 and BL60
BL23 gives the lower-back comparison. BL60 gives the outer-ankle comparison. BL40 sits between them in the reader's map, but the three pages do not create a pressure sequence. Each body area has its own stop signs.
The wrong way to read BL40
The wrong reading is: a distant knee point is safer than touching the back, so use BL40 when the back hurts. A safer reading is: BL40 explains a traditional relationship, while actual back, knee, or leg symptoms may need care or rest.
Technique boundaries for BL40
This page does not teach acupuncture, moxa, cupping, scraping, pressure dosing, massage behind the knee, or back-care planning. It keeps professional technique and personal symptom judgment outside the article.
Best next page after BL40
Choose BL23 for lower-back vocabulary, BL60 for ankle comparison, or the desk routine for mild posture context. Choose Safety or qualified care when the knee, leg, or back symptom is swollen, painful, numb, severe, persistent, injury-related, or unusual.
Full-page decision frame for BL40
BL40 Weizhong, Middle of the Crook, deserves more than a chart label because the reader has to make several separate decisions before touching the back of knee. The first decision is identity: this is a Bladder point, not a general label for every nearby tender place. The second decision is context: leg and back tradition references is a traditional or wellness reading cue, not a promise that pressure changes a personal condition. The third decision is safety: avoid varicose veins, swelling, or clot concerns. A full page for Middle of the Crook therefore has to slow the reader down. It names the point, describes the broad locator, explains why the point appears with certain routines, separates acupressure from professional techniques, and gives a conservative next page. If the reader only wants a quick answer, the safest quick answer is still narrow: read the locator, check the stop signs, and use the point only as education unless the situation is mild and comfortable.
How to verify the back of knee landmark
BL40 starts with the back of knee view, but the visual marker is only a region finder. The written landmark carries the real work: At the back of the knee crease, in a sensitive soft-tissue area. Avoid varicose veins, swelling, clot concerns, or strong pressure behind the knee. This matters for Middle of the Crook because readers often arrive after seeing a short social post, wrist band, point chart, or routine list. A chart can make the target look cleaner than a real body feels. The reader should first name the broad body area, then compare the landmark with bones, tendons, folds, or soft tissue nearby, then check whether the skin and sensation are normal. If the reader cannot repeat the landmark in plain English, BL40 should remain a reading page. If the body area is painful, numb, swollen, bruised, hot, wounded, recently injured, or hard to interpret, the locator has already done its job by telling the reader to stop.
What leg and back tradition references means on this page
The phrase leg and back tradition references explains why BL40 appears in this atlas, but it does not turn Middle of the Crook into a personal answer. For Weizhong, the use context is a signpost for reading related pages, not a guarantee, not a ranking, and not a reason to ignore symptoms. A better way to read the phrase is: people commonly encounter this point while researching leg and back tradition references, so the page should explain the name, locator, safety limits, and nearby choices clearly. That is very different from saying the point handles the concern. If the concern is mild and ordinary, BL40 can be part of a conservative reading path. If the concern is severe, new, persistent, frightening, pregnancy-related, medication-related, child-related, post-surgery, or connected with chronic illness, the leg and back tradition references phrase becomes less important than the safety path.
How BL40 relates to nearby point pages
Middle of the Crook should be compared with related pages only one relationship at a time. Useful comparison points include BL2 Zanzhu (inner eyebrow), BL23 Shenshu (lower back), BL60 Kunlun (outer ankle), ST36 Zusanli (front outer lower leg). The relationship may come from the same meridian, the same body region, a similar routine page, or a shared beginner question, but those relationships do not make the points interchangeable. BL2 Zanzhu has its own locator and caution; BL23 Shenshu has another. For BL40, the right comparison question is not "which point is stronger?" but "which page answers my current job?" A culture page explains the name. A printable page preserves memory. A wellness page compares a mild scenario. A safety page interrupts action. Reading those pages in the right order keeps Weizhong from becoming one more item in a long, unfocused list.
When pairing BL40 with another point makes sense
Pairing BL40 with another point is a reading decision before it is a physical routine. The safest pairing starts on a guide such as Desk Routine for Neck and Shoulder Tension, where the page can explain why several points appear together and which stop sign controls the whole set. For Middle of the Crook, pairing is most useful when it clarifies roles: one point may be the main locator to read, another may be a comparison point, and another may be a reason to leave the routine for Safety. Pairing is not useful when it simply adds more body areas because more points sound more complete. Each added point adds a new landmark, new tissue, and a new way to misread discomfort. If the reader cannot explain why BL40 belongs with the next point, the better step is to read one full page and stop.
Using BL40 inside a short routine
Middle of the Crook may appear in a mild self-care reading path, but the routine has to stay education-first and stop-first. A short routine around BL40 should have a beginning, a check, and an end. The beginning is the safety review: avoid varicose veins, swelling, or clot concerns. The check is the locator review: At the back of the knee crease, in a sensitive soft-tissue area. The end is a conscious decision to stop, continue reading, or open a related page. If gentle contact is appropriate, it should stay brief, comfortable, and easy to release. The reader should not chase a deep ache, try to create sensation, or keep pressing because a point name sounds important. A routine also should not stack BL40 with every point on the Bladder line. The page works best when it turns a vague impulse into one narrow action: read, locate broadly, touch lightly only if low risk is clear, and stop if the body gives any reason to stop.
Acupuncture, moxa, and cupping boundaries for BL40
BL40 can appear in professional acupuncture, moxibustion, or cupping contexts, but this page does not teach those methods. Acupuncture involves needles and belongs with qualified professional practice. Moxibustion involves heat, smoke, fire, burn risk, and pregnancy caution. Cupping involves suction, bruising, skin status, blood-thinner concerns, and injury questions. Those techniques are not stronger home versions of acupressure. For Middle of the Crook, the public page can explain that the same named point may appear across modalities, but it cannot convert professional technique language into instructions. If a reader came here searching for needling effects, moxa application, cupping placement, or stronger results, the safe answer is to stay in education mode and use qualified care or a licensed practitioner rather than improvising on the back of knee.
Wrong turns readers make with Middle of the Crook
A frequent wrong turn is to treat tenderness near BL40 as proof that the point was found. Tenderness can mean pressure is too strong, the tissue is irritated, or the wrong body area is being tested. Another wrong turn is to use leg and back tradition references as a shortcut around safety. A third is to keep moving across the back of knee until something feels intense. For Middle of the Crook, intensity is not the goal. Clarity is the goal. The reader should be able to say: this is the Bladder point Weizhong, the locator is At the back of the knee crease, in a sensitive soft-tissue area., the caution is avoid varicose veins, swelling, or clot concerns, and my next step is either read-only, gentle and brief, a related page, or qualified help. If that sentence cannot be said honestly, the page has not cleared pressure.
When BL40 is not the right next page
BL40 is not the right next page when the reader is trying to decide whether a symptom is serious, whether medicine can be changed, whether pregnancy or child use is safe, or whether an injury can be worked around. It is also not the right page when leg swelling, varicose veins, clot concern, bruising, numbness, or injury are present. In those cases, opening more point pages can create false momentum. The better route is a safety page, a professional conversation, or emergency guidance when warning signs are present. The value of the Middle of the Crook article remains intact even when the answer is not to press. It still gives language, location context, visual orientation, and relationships. A high-quality point page is allowed to say that the most useful next action is leaving the point page.
How the printable card should depend on this page
The printable BL40 card should be treated as a reminder after this full article, not as the article itself. A card can remember Weizhong, Middle of the Crook, the broad back of knee cue, and the stop signs, but it cannot carry the full context around leg and back tradition references, related points, source limits, or technique boundaries. For BL40, the card is useful when the reader has already read the landmark and wants a small memory aid. It is not useful when separated from the safety note, used during a high-risk situation, or shared as a quick instruction. If a card and the full page disagree in the reader's mind, the full page wins. If the card makes the action feel too easy, return to the full page or Safety.
Source and visual notes for Middle of the Crook
The source notes on BL40 have different jobs. Nomenclature and location sources keep BL40 Weizhong aligned with standard naming and broad locator language. Safety and health-information sources keep the page from becoming personal advice. The visual source identifies the licensed anatomy base used for orientation; it does not prove exact placement on any reader's body. For Middle of the Crook, that split is important because source lists can look more authoritative than they are. A source can support a name, a boundary, a cultural context, or a visual credit, but it cannot inspect the reader, confirm a symptom, clear an injury, or promise that leg and back tradition references will improve. The trustworthy reading is modest, traceable, and limited.
Final choice after reading BL40
End the Middle of the Crook page with one of four choices. Choice one is read-only: the reader understands BL40 better but does not touch the back of knee. Choice two is a brief gentle contact: the situation is mild, the skin and tissue feel normal, the landmark is clear, and the reader can release immediately. Choice three is a related page: the reader needs Desk Routine for Neck and Shoulder Tension, a name-meaning page, a printable memory aid, or a safety answer before acting. Choice four is qualified care: the concern is personal, severe, persistent, unusual, pregnancy-related, medication-related, child-related, chronic-condition-related, injury-related, or unclear. The page is successful when the reader can choose among those outcomes without relying on a chart alone. BL40 is a named point, but the decision is the real product.
Relationship map after BL40
BL40 should leave the reader with a relationship map, not just a locator. Start with the point itself: Weizhong, translated here as Middle of the Crook, sits in the Bladder context and uses the back of knee cue. Then compare neighboring reading paths: BL2 Zanzhu on the inner eyebrow; BL23 Shenshu on the lower back; BL60 Kunlun on the outer ankle; ST36 Zusanli on the front outer lower leg; SP6 Sanyinjiao on the inner lower leg. Those pages are not backup targets to press if BL40 feels uncertain; they are separate articles with separate body areas, cautions, and purposes. The broader use-case map is Desk Routine for Neck and Shoulder Tension. Use those pages only when the concern is mild enough to remain in education and safety navigation. This map is important because many people search for a point by discomfort, then keep adding pages until something feels persuasive. A better habit is to ask which relationship explains the next decision. If the next decision is name meaning, open Culture. If it is a memory aid, open Printable. If it is a combination, open the matching wellness guide. If it is risk, leave BL40 for Safety. The map keeps Middle of the Crook from becoming a loose claim about leg and back tradition references.
What the reader can safely take away from BL40
A careful takeaway from BL40 has five parts. First, remember the identity: BL40 Weizhong, Middle of the Crook, is a named point, not a universal body button. Second, remember the place: At the back of the knee crease, in a sensitive soft-tissue area. Third, remember the caution: avoid varicose veins, swelling, or clot concerns. Fourth, remember the use-language limit: leg and back tradition references explains why the point appears in traditional and wellness reading paths, but it cannot decide a personal symptom or promise an outcome. Fifth, remember the next action: read only, use a brief gentle contact only when low-risk context is obvious, compare one related page, or ask qualified care. This takeaway is intentionally practical. It gives the reader something to do with the page without turning the page into medical advice. For Middle of the Crook, the best result is not that the reader presses more confidently. The best result is that the reader can explain why this point fits, why it does not fit, or why the question belongs outside the atlas today.
What sources support beside the evidence note for BL40
Reader use: for BL40 Weizhong, the recalled sources support the exact article identity at /acupoints/bl40-weizhong/, the displayed point name, and the broad locator language used on this page rather than a generic chart. Reader use: for BL40 Weizhong, the named sources support the page-specific boundary "This BL40 page is educational and not medical advice. It cannot assess knee pain, leg swelling, vascular concerns, ba..." and the article value "A back-of-knee point article that explains why a back-related point still needs knee and leg caution." without promising a result. Read these notes as traceability for this one point page; they cannot inspect the reader's skin, medication, pregnancy status, chronic illness, pain pattern, urgency, or whether pressure belongs today.
Questions Readers Usually Ask
Why is a back-of-knee point linked to back pages?
The link comes from traditional Bladder meridian mapping. It is a reading relationship, not a back-pain routine.
Can I press BL40 if my leg is swollen?
No. Swelling, varicose-vein concern, clot concern, injury, numbness, severe pain, or unexplained leg symptoms should stop pressure.
Is BL40 safer than pressing the lower back?
Not automatically. The back of the knee has its own cautions, and it does not solve back warning signs.
Sources Used
For BL40 Weizhong: Back-of-Knee Point, Back Relationship, and Safety, these notes are tied to this page asset: A back-of-knee point article that explains why a back-related point still needs knee and leg caution. They show which references support names, location terms, safety boundaries, cultural context, visual attribution, or content-check wording. They do not assess your symptoms, medication, pregnancy status, skin, or personal health situation for this page.
World Health OrganizationWHO Standard Acupuncture NomenclatureReader note: Used to keep point codes, pinyin naming, and meridian labels consistent. Not used as evidence that a point works for a health condition.Reader use: Used to keep point codes, pinyin naming, and meridian labels consistent. Not used as evidence that a point works for a health condition.World Health Organization Western Pacific RegionWHO Standard Acupuncture Point Locations in the Western Pacific RegionReader note: Used for broad location discipline and to avoid inventing locator certainty. Not used to make a public body-map marker clinically exact.Reader use: Used for broad location discipline and to avoid inventing locator certainty. Not used to make a public body-map marker clinically exact.NIH MedlinePlusKnee Injuries and DisordersReader note: Used for back-of-knee cautions on BL40 and lower-leg relationship pages. Not used to decide whether knee pain, swelling, or vascular concern is safe for pressure.Reader use: Used for back-of-knee cautions on BL40 and lower-leg relationship pages. Not used to decide whether knee pain, swelling, or vascular concern is safe for pressure.NIH MedlinePlusLeg Injuries and DisordersReader note: Used for lower-leg swelling, varicose-vein, clot-concern, and shin-tissue boundaries. Not used to evaluate leg swelling, clot risk, injury, or suitability for pressure.Reader use: Used for lower-leg swelling, varicose-vein, clot-concern, and shin-tissue boundaries. Not used to evaluate leg swelling, clot risk, injury, or suitability for pressure.NIH MedlinePlusBack PainReader note: Used for back and spine-adjacent stop signs on lower-back, desk, and Bladder meridian point pages. Not used to identify a cause of back pain or clear pressure near the spine.Reader use: Used for back and spine-adjacent stop signs on lower-back, desk, and Bladder meridian point pages. Not used to identify a cause of back pain or clear pressure near the spine.Standardization Administration of ChinaGB/T 12346-2021 Nomenclature and Location of Meridian PointsReader note: this source supports standardized point names, codes, and location vocabulary.Reader use: check standardized point codes, Chinese names, and location vocabulary for BL40 Weizhong; do not treat naming precision as personal clearance.World Health OrganizationWHO Standard Acupuncture NomenclatureReader note: this source helps keep acupoint codes and English naming consistent across pages.Reader use: compare BL40 Weizhong with international acupoint code and naming conventions, not with symptom advice.NCCIHAcupuncture: Effectiveness and SafetyReader note: this source supports cautious evidence wording and the education-only boundary.Reader use: understand cautious evidence, safety limits, and the education-only boundary around Bladder naming, back of knee location cues, and leg and back tradition references.Servier Medical ArtServier Medical Art human anatomy imagesReader note: this source provides the licensed human-body base images under CC BY 4.0 attribution.Reader use: recognize BL40 Weizhong's licensed human-body base as a visual orientation aid, not clinical point placement.