BL-41 (Fu Fen) Attached Branch

What does BL-41 Fu Fen do?

Fu Fen BL-41 is the first and highest point of the outer Bladder line, three cun out from the midline at the second thoracic vertebra, level with Feng Men BL-12 an inch and a half in — and its recorded work is entirely local and musculoskeletal: it activates the channel and alleviates pain, and it expels wind and cold. Sacred Lotus sources & references record those two actions and classify it as a Meeting Point of the Bladder and Small Intestine channels. It carries no five-shu, source, connecting, cleft, back-shu or front-mu classification. Among the points of the upper back it is one of the plainest: a shoulder, neck and upper-back point, with none of the organ or spirit associations that its neighbours below it carry.

• Activates the channel and alleviates pain — the primary recorded action and the reason for almost every use of the point. BL-41 lies in the band of muscle between the spine and the inner edge of the shoulder blade, at the level where the neck meets the upper back, and stiffness, aching and restriction in exactly that band are what it is reached for.
• Expels wind and cold — the pattern-based action. In the classical account wind and cold invade the body through the upper back and the nape, and the points of this region are the ones used to drive them out again. It is the reasoning that also gives the neighbouring Feng Men BL-12 its name, "Wind Gate".
• Reaches the Small Intestine channel as well as the Bladder channel — a consequence of the meeting-point classification rather than a separate action, but a practical one. The Small Intestine channel runs over the shoulder blade and the back of the shoulder, which is where BL-41's pain territory lies, so the classification and the indications agree with each other.

What BL-41 does not claim, stated plainly because its neighbours make readers expect it. The five best-known points of the outer Bladder line are named for the five spirits and are used for the mental and emotional register of the organs beside them. BL-41 is not one of them, and our own data record no such action for it. Its two neighbours illustrate the difference: Po Hu BL-42 directly below is named for the po, the corporeal soul housed by the Lungs, and Gao Huang Shu BL-43 below that is the classical point of last resort for deep depletion. BL-41 is neither. It is a musculoskeletal point in a famous neighbourhood, and that is the accurate description.

Source: Sacred Lotus sources & references (channel, the Meeting Point classification, and the existing action record — reformatted here from a broken bare list run; the BL-12, BL-42 and BL-43 records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 301; Chinese Acupuncture & Moxibustion, p. 184; cross-referenced against multiple online sources.

What is BL-41 Fu Fen used for?

Fu Fen BL-41 is used for pain and stiffness of the shoulder, upper back and neck, and for numbness running into the elbow and arm — a narrow and consistent list, all of it musculoskeletal. The indications carried in Sacred Lotus sources & references are stiffness and pain of the shoulder, back and neck, and numbness of the elbow and arm. The standard reference literature adds little beyond that. These describe traditional use, not proven treatment. This point lies over the thorax and carries the pneumothorax considerations set out under needling.

• Stiffness and pain of the shoulder
• Pain and tightness in the upper back, between the shoulder blade and the spine
• Rigidity of the neck and difficulty turning the head
• Numbness of the elbow and arm
• Numbness and aching along the outer arm following the shoulder
• Contraction and spasm of the muscles of the upper back
• Aversion to cold and wind affecting the nape and shoulders — the wind-cold presentation
• Pain that worsens with cold or draught in this region

The shortness of the list is the point. Most points on the upper back carry a long indication list because they connect to an organ. BL-41 does not, and our own record for it is correspondingly brief — three musculoskeletal complaints and nothing else. That is not an omission in our data; it is what the standard references record. A reader looking for cough, asthma or a spirit indication at this level should look at Feng Men BL-12 on the inner line, at Po Hu BL-42 directly below, or at Fei Shu BL-13 — all held here.

Source: Sacred Lotus sources & references (existing indication record, reformatted here as a list from a bare comma-run; the BL-12, BL-13 and BL-42 records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 301; Chinese Acupuncture & Moxibustion, p. 184; cross-referenced against multiple online sources.

Where is BL-41 Fu Fen, and how is it used in practice?

Fu Fen lies on the upper back, three cun out from the midline — roughly a hand's breadth to the side of the spine — level with the lower edge of the second thoracic vertebra, and therefore level with Feng Men BL-12 an inch and a half in. At that distance it sits on or very near the inner border of the shoulder blade. Sacred Lotus sources & references hold two location records and they agree, one adding that the point lies on the spinal border of the scapula. Those two points, plus the midline of the spine, sit on one horizontal line across the upper back, and knowing that line is how BL-41 is found: locate the T2 spinous process, move out to BL-12, keep going the same distance again.

A location discrepancy, flagged and not adopted. A 2023 scholarly paper argues, from ancient literature, the acupuncture Mingtang charts and the bronze acupuncture statue, that Da Zhui DU-14 should be positioned under the spinous process of the first thoracic vertebra rather than the seventh cervical, and Yao Yang Guan DU-03 under the fifth lumbar rather than the fourth — and that consequently the other points of these channels should each be moved down by one vertebra (Zhongguo Zhen Jiu 2023;43(10):1184–1188, PMID 37802527). If accepted, that would shift the vertebral referencing of the entire back, BL-41 included. Our recorded location is kept unchanged: both of our location records, and the standard reference texts they derive from, place BL-41 at the second thoracic vertebra level with BL-12. The paper is a minority scholarly argument about the whole numbering convention rather than a finding about this point, and it is recorded here so that a reader who meets it knows we have seen it and why our location stands.

In practice BL-41 is used as a local point and almost nothing else. It is chosen for pain that sits out along the inner edge of the shoulder blade and up into the neck rather than close to the spine, because that is exactly where it lands, and it is very commonly treated by moxibustion, cupping or massage rather than by needle — the upper back being one of the regions where non-needle techniques do most of the work.

Which points is BL-41 combined with?

• With Feng Men BL-12 — the inner-line point at the same T2 level, held here and classified in our own records as a Meeting Point of the Bladder channel with the Governing Vessel. The two are the inner and outer members of one horizontal line, and the pairing is the standard one for wind-cold affecting the upper back and nape.
• With Da Zhu BL-11 and Fei Shu BL-13 — the inner-line points above and below, both held here. BL-11 is the Hui-Meeting Point of the Bones and, in our own records, a Meeting Point of the Bladder, Small Intestine, San Jiao and Gall Bladder channels with the Governing Vessel; BL-13 is the Lung Back-Shu point.
• With Po Hu BL-42 and Gao Huang Shu BL-43 — its immediate neighbours below on the outer line, both held here, and both far better known than BL-41 itself.
• With Jian Wai Shu SI-14 and Tian Zong SI-11 — Small Intestine channel points over and around the shoulder blade, both held here. Queried directly, our own record places SI-14 three cun lateral to the T1 spinous process, which puts it one level above BL-41 on the same vertical line — the two are near neighbours despite belonging to different channels, and BL-41's Small Intestine meeting classification is the theoretical expression of that adjacency.
• With Jian Jing GB-21 — on the top of the shoulder, held here, the standard point for shoulder and neck tension and a member of the same hazardous band above the lung.
• With Tian Zhu BL-10 — at the back of the neck, held here, added where the stiffness runs up into the nape.
• With the extra point Ding Chuan — beside the seventh cervical vertebra, held here, and part of the same band.
• With Hou Xi SI-03 — the Confluent Point of the Governing Vessel at the side of the hand, held here, and the standard distal point for stiffness of the neck and upper back.

Does BL-41 belong to the five outer-line "spirit" points?

No — and this was checked directly against our own records rather than assumed. BL-41 is a point on the outer Bladder line, but it is not one of the five spirit points, and the list of five is correct as it stands. The reason is a matter of what the outer line pairs with. The Bladder channel runs down the back in two parallel lines: the inner line at one and a half cun carries the Back-Shu points, and the outer line at three cun runs alongside it. At the level of each of the five yin-organ Back-Shu points, the outer line carries a point named for the spirit aspect of that same organ:

• BL-42 Po Hu, "Po Door" — level with BL-13 Fei Shu, the Lung Back-Shu point. The po, corporeal soul.
• BL-44 Shen Tang, "Spirit Hall" — level with BL-15 Xin Shu, the Heart. The shen, spirit proper.
• BL-47 Hun Men, "Hun Gate" — level with BL-18 Gan Shu, the Liver. The hun, ethereal soul.
• BL-49 Yi She, "Reflection Abode" — level with BL-20 Pi Shu, the Spleen. The yi, thought.
• BL-52 Zhi Shi, "Will Chamber" — level with BL-23 Shen Shu, the Kidneys. The zhi, will.

BL-41 is level with Feng Men BL-12, which is not a yin-organ Back-Shu point at all — queried directly, our own record classifies BL-12 as a Meeting Point of the Bladder channel with the Governing Vessel. There is no organ at that level for a spirit point to belong to, and BL-41's name refers to nothing of the kind. So the set remains five, not six, and our BL-42 and BL-52 records are right about it.

What BL-41 is is the top of the outer line — and the outer line is longer than the spirit set. Queried directly, Sacred Lotus sources & references hold the complete outer Bladder line: all fourteen points at three cun lateral, from BL-41 down to BL-54 — BL-41 Fu Fen, BL-42 Po Hu, BL-43 Gao Huang Shu, BL-44 Shen Tang, BL-45 Yi Xi, BL-46 Ge Guan, BL-47 Hun Men, BL-48 Yang Gang, BL-49 Yi She, BL-50 Wei Cang, BL-51 Huang Men, BL-52 Zhi Shi, BL-53 Bao Huang and BL-54 Zhi Bian. Nine of those fourteen are neither spirit points nor organ points; they are named for other things entirely. Fu Fen BL-41 is the first of the fourteen and the highest point on the line — the one a reader coming down the outer line meets first.

Source: Sacred Lotus sources & references (both location records; the complete fourteen-point outer Bladder line and the BL-10, BL-11, BL-12, BL-13, BL-15, BL-18, BL-20, BL-23, BL-42, BL-43, BL-44, BL-47, BL-49, BL-52, SI-03, SI-11, SI-14, GB-21 and Ding Chuan records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 301; Chinese Acupuncture & Moxibustion, p. 184; Ling Shu (Spiritual Pivot), chapter 8, on the five spirits and the organs that house them; PMID 37802527 (location proposal flagged, not adopted) — verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.

Where is BL-41 located?

• A Manual of Acupuncture (p. 301): 3 cun lateral to the midline, level with the lower border of the spinous process of the second thoracic vertebra (T2) and level with Fengmen BL-12.
• Chinese Acupuncture and Moxibustion (p. 184): 3 cun lateral to the Governor Vessel, at the level of the lower border of the spinous process of the second thoracic vertebra, on the spinal border of the scapula.

How is BL-41 Fu Fen needled, and what is the pneumothorax risk?

Stated plainly: BL-41 lies over the thorax beside the second thoracic vertebra, with the apex and upper lobe of the lung beneath it, and pneumothorax — a punctured lung — is the documented hazard at this point and at every point in the band it belongs to. Sacred Lotus sources & references record perpendicular insertion of 0.3 to 0.5 inch with moxibustion applicable; the reference texts additionally record oblique insertion directed medially, toward the spine. The bounded figure is the substance of that record, not a formality. Everything below is recorded as neutral reference data describing what the textbooks and the published anatomical studies document. It is not instruction, this page does not teach technique, and needling is carried out only by a qualified, licensed practitioner.

The angle and depth the texts record

• Sacred Lotus sources & references record perpendicular insertion of 0.3 to 0.5 inch, with moxibustion applicable. That is one of the shallowest figures held in this library, and it belongs to the whole upper thoracic band rather than to this point alone.
• Deadman & Al-Khafaji (p. 301) and Chinese Acupuncture & Moxibustion (p. 184) record oblique insertion directed medially, toward the spine, in a comparable range, with an explicit caution against deep or laterally angled insertion at the thoracic points because of the lung beneath. The geometry is the whole point: angling toward the vertebral column keeps the needle in the muscle mass with bone behind it, while angling outward points it at the intercostal space and the pleura behind that.
• Moxibustion, cupping and massage are all recorded here and are extremely common at this point. None carries the pneumothorax hazard, which is one reason the upper back is so often treated without needles at all.
• An anatomical note specific to BL-41. At three cun lateral, BL-41 lies on or very near the medial border of the scapula in many people, and our own location record says so explicitly. Where the shoulder blade lies beneath the point there is bone between the needle and the chest wall; where the arm is drawn forward and the scapula slides laterally, there is not. The margin at this point is therefore not a fixed quantity even in the same person.

What has actually been measured at this point

• A CT study measured BL-41 itself — and this is its own figure, not a neighbour's. A retrospective study measured, directly from chest CT images, the safe needling depth at 23 upper-back acupoints in 319 patients aged 4 to 18 (205 boys, 114 girls) at a single Taiwanese hospital. The 23 points were DU-09 to DU-14, BL-11 to BL-17, BL-41 to BL-46, SI-14, SI-15, GB-21 and SP-21. Safe depth is defined differently by point in that paper, and the difference matters here: for the Governing Vessel points on the midline it is the distance from skin to the epidural layer, while for the off-midline points — BL-41 among them — it is the distance from the skin surface to the pleura. The measured skin-to-pleura depth at Fu Fen BL-41 was 30.86 ± 9.20 mm in boys and 28.21 ± 7.89 mm in girls. Depths differed significantly by age, by weight and by body mass index across the point set, and multiple regression identified weight as the single most important determinant at all 23 points (Ma YC et al., BMC Complement Altern Med 2016;16:85, PMID 26922245, PMC4769822, DOI 10.1186/s12906-016-1060-x). State the limits precisely: these are children and adolescents, they are hospital patients rather than healthy children, they come from a single centre and a single population, and the figure is the distance at which the pleura is reached — a measurement, not a recommended needling depth. No adult measurement at this point was located and none is quoted.
• Why that figure is worth reading twice. Three centimetres, in a child, is the entire margin — and the standard deviation of just over nine millimetres in boys means individual children in the same study differed from one another by more than the whole textbook insertion range. It is also worth noting what BL-41's number means relative to its neighbours: at 30.86 mm in boys it is deeper than Po Hu BL-42 below it (28.02 mm) and considerably deeper than the lower outer-line points BL-44 (20.31 mm), BL-45 (18.45 mm) and BL-46 (18.16 mm). The outer line gets thinner as it descends, because the bulk of trapezius and the shoulder blade is greatest at the top. BL-41 sits at the thickest part of it — which is the one genuinely reassuring fact about this point, and it is a fact about tissue rather than about technique.
• The cadaveric pleural-dome study did not name BL-41. A dissection study of 46 adult bodies mapped the dome of the pleura against the points around it, naming Da Zhu BL-11, Tian Tu REN-22, Jian Jing GB-21, Qi She ST-11 and Ding Chuan. The dome extended beyond the medial third of the clavicle in almost 60 per cent of bodies, and the authors concluded that when a point is located and angled as the standard describes the pleura is not reached, but that exceeding the recorded depth breaches the pleural membrane (Chen Y et al., Zhongguo Zhen Jiu 2006;26(5):346–348, PMID 16739850). BL-41 is not in that list, and the finding is cited for the region rather than as a measurement of this point.
• The nearest measured adult figure in this region belongs to a different point. Ultrasonography in 101 adults measured the vertical distance from skin to pleural line at Jian Jing GB-21 as a mean of 17.4 mm in men and 14.6 mm in women, increasing with weight, height and body mass index (Lin S-K et al., J Acupunct Meridian Stud 2018;11(6):355–360, PMID 29936338). That is GB-21's figure, not Fu Fen's.
• No single agreed safe depth exists for any point. Two systematic reviews of the safe-depth literature — 33 studies in one, 47 in the other, by MRI, CT, ultrasound and cadaveric dissection — both concluded that measured depths for the same point differ greatly between subject groups and measuring methods, and that "safe depth" has never been standardised (J Altern Complement Med 2011;17(3):199–206, PMID 21417806; Evid Based Complement Alternat Med 2013;2013:740508, PMID 23935678).
• What lies beneath, in plain terms. At the T2 level, three cun from the midline, a needle passes through skin, subcutaneous tissue, trapezius and rhomboid, and then meets either the shoulder blade — solid bone — or, where the scapula has moved, the second and third ribs with the intercostal space between them, the parietal pleura, and the apex of the lung behind it. That is the whole anatomical reason for the recorded medial angle and shallow depth.

What is documented, and in what proportion

Pneumothorax is the second most frequently reported serious adverse event in acupuncture. A systematic review of the Chinese case-report literature from 1956 to 2010 identified 1,038 adverse-event cases across 167 articles, of which 307 were pneumothorax — behind only fainting — with 35 deaths across the whole series; the authors attributed the events chiefly to improper technique and judged most avoidable (He W et al., J Altern Complement Med 2012;18(10):892–901, PMID 22967282). A companion review of 115 Chinese-language articles reporting 479 adverse events including 14 deaths reached the same conclusion (Zhang J et al., Bull World Health Organ 2010;88(12):915–921C, PMID 21124716, PMC2995190). Presentation is not always immediate: an emergency-medicine case report describes a healthy 38-year-old woman who developed pleuritic chest pain the day after dry needling of the back, with bedside ultrasound showing absent lung sliding (Cureus 2021;13(3):e14207, PMID 33948398, PMC8086747). Fatal cases exist: an autopsy report describes bilateral pneumothoraces following electroacupuncture, the authors noting that electrical pulses and the muscle contraction they cause may draw needles deeper than the depth at which they were inserted (J Forensic Sci 2022;67(1):377–383, PMID 34435369).

What we will not claim. None of those reviews identifies the individual points involved, and no published case report naming Fu Fen BL-41 specifically as the site of a pneumothorax was located. No such claim is made here. A pneumothorax after needling over the upper back may declare itself hours later with sudden chest pain, breathlessness or a persistent dry cough, and is a medical emergency requiring immediate assessment.

Risk in proportion. A meta-analysis of prospective clinical studies estimated serious adverse events at approximately 1 per 10,000 patients and around 8 per million treatments, with about half of all recorded events being bleeding, pain or flare at the needle site (Bäumler P et al., BMJ Open 2021;11:e045961, PMID 34489268). Both facts belong together: the overall rate is low, and the events that do occur concentrate in the band of points over the lung to which Fu Fen belongs.

Source: Sacred Lotus sources & references (existing needling record and both location records; the BL-42, BL-44, BL-45, BL-46 and GB-21 records queried directly for comparison); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 301; Chinese Acupuncture & Moxibustion, p. 184; PMID 26922245 (PMC4769822) — BL-41's own figure used, skin-to-pleura; PMID 16739850 (naming BL-11, not BL-41); PMID 29936338 (GB-21's figure); PMID 21417806; PMID 23935678; PMID 22967282; PMID 21124716 (PMC2995190); PMID 33948398 (PMC8086747); PMID 34435369; PMID 34489268 — each verified resolvable and checked for retraction status before citation.

What does the name Fu Fen mean?

Fu Fen means "Attached Branch" — fu, to attach, adjoin or be appended to, and fen, a branch, a division, a part separated off. Sacred Lotus sources & references translate it exactly that way. The name is structural rather than functional: it does not say what the point does, it says where the point sits in the layout of the channel. This is where the Bladder channel divides on the back into two parallel lines, and BL-41 is the first point of the branch that separates off — the branch attaching to the main line. Read that way the name is a piece of channel cartography, and it is the most informative thing about the point.

That reading has a consequence worth noticing. Most acupuncture point names describe a place on the body, an action, or an image — a mountain, a gate, a spring, a spirit. A name that describes the point's position in the channel system rather than on the body is unusual, and it marks BL-41 as the point that exists to open the second line rather than for anything it does. Everything else on the outer line has a name of its own kind: doors, halls, chambers, granaries, gates. BL-41 is simply the branch, attached.

Why does it matter that BL-41 is a meeting point?

Meeting points are where two or more channels cross, and they are chosen when one needle should influence all of them. Sacred Lotus sources & references classify BL-41 as a Meeting Point of the Bladder and Small Intestine channels. That is not decorative here: the Small Intestine channel runs over the shoulder blade and around the back of the shoulder, which is exactly the region BL-41's recorded indications describe. Its neighbour Da Zhu BL-11 two levels up is classified in our own records as a meeting point of four channels and the Governing Vessel — the upper back is the most crossed-over region on the body, which is why so many of its points carry meeting classifications.

Is there research on BL-41 Fu Fen?

There is no point-specific clinical research on BL-41, and that should be said plainly rather than filled in with studies of protocols that happen to contain it. The only published work that measured this point is anatomical.

• The paediatric chest-CT safe-depth study measured this point. The imaging work described under needling (PMID 26922245, PMC4769822) measured Fu Fen BL-41 directly among 23 upper-back points in 319 children and adolescents and published a figure for it — 30.86 ± 9.20 mm in boys and 28.21 ± 7.89 mm in girls, skin to pleura. It is anatomical rather than clinical, and it is the single most useful published finding about this point.
• A location paper mentions the level, not the point's use. The 2023 argument about the vertebral referencing of DU-14 and DU-03 (PMID 37802527), set out and flagged under practice above, bears on where BL-41 is counted from rather than on what it does.
• Nothing else. No randomised trial isolates BL-41; no trial of BL-41 for shoulder pain, neck stiffness, arm numbness or any other recorded indication was located; and no case report or observational study naming the point was located.

A point-code caution, recorded because it was met while assembling this. Searching the literature for this point by name is nearly useless. The pinyin "Fufen" returns a single record — the location paper above — and it does not concern the point's clinical use. Searching the code "BL 41" without qualification returns matches to ordinary text throughout the biomedical literature and is worthless. Every record considered for this page was read rather than counted, and the honest total is one anatomical measurement.

How does Fu Fen differ from the points near it?

Feng Men BL-12 is the inner-line point at the same T2 level, held here — the "Wind Gate", the classical point for wind invasion of the upper back, and by a wide margin the busier of the two. Where BL-41 offers a local muscular action, BL-12 offers the exterior-releasing one. Po Hu BL-42 lies directly below BL-41 on the outer line at T3, level with Fei Shu BL-13, and is the first of the five outer-line spirit points. Gao Huang Shu BL-43 lies below that at T4 and is the famous point of last resort for consumptive and deeply depleted conditions — the best-known point of the whole outer line, and the one BL-41 is most often confused with by a reader counting down from the top. Da Zhu BL-11 at T1 on the inner line is the Hui-Meeting Point of the Bones. Jian Wai Shu SI-14 lies three cun lateral at the T1 level — the same vertical line as BL-41, one level up, on a different channel. Jian Jing GB-21 lies laterally on the top of the shoulder, and the extra point Ding Chuan beside the seventh cervical vertebra; both are in the same hazardous band and both are held here. Because the outer line has no palpable landmark of its own and must be counted from the vertebrae, BL-41, BL-42 and BL-43 are genuinely easy to mistake for one another — which is one practical reason to know that only BL-41 lacks any organ or spirit association.

Source: Sacred Lotus sources & references (name, translation, channel, the Meeting Point classification, the complete fourteen-point outer Bladder line, and the BL-11, BL-12, BL-13, BL-42, BL-43, BL-44, BL-47, BL-49, BL-52, SI-14, GB-21 and Ding Chuan records queried directly); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 301; Chinese Acupuncture & Moxibustion, p. 184; Ling Shu (Spiritual Pivot), chapter 8, on the five spirits; PMID 26922245 (PMC4769822); PMID 37802527 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.