BL-50 (Wei Cang) Stomach Granary

What does BL-50 Wei Cang do?

BL-50 harmonises the middle jiao — a single recorded action, the shortest action record of any point on the outer Bladder line.

• Harmonises the middle jiao — the whole of the recorded action

Name, level and partner all say “stomach”. “Wei Cang” means Stomach Granary, and BL-50 sits level with BL-21 Wei Shu — Stomach Shu, the Back-Shu point of the Stomach — on the inner line at T12. Both names carry wei, the stomach. Our BL-46 record documents the same explicit naming pair with BL-17 Ge Shu, and our BL-48 record traces the pattern across the whole outer line. Where the naming makes the inner-and-outer pairing visible, this library points it out, because it is one of the few places the system explains itself.

A cang is a granary or storehouse, and the image is of the stomach as the store from which the body is fed — the classical account of the middle burner as the source of acquired qi. The name is functional in that sense rather than anatomical.

Where BL-50 sits in the run. The outer line above it — BL-41 to BL-49 — runs down the thoracic back over the ribs. BL-50 is at T12, the last thoracic level, and below it BL-51, BL-52 and BL-53 continue into the lumbar and sacral regions. That position is not just numbering: it is where the anatomy beneath the line changes, which the needling section sets out.

Source: Sacred Lotus sources & references (channel, action, location and translation records; the BL-21, BL-46, BL-48, BL-51, BL-52 and BL-53 records queried and compared against our own data), cross-referenced against multiple online sources.

What is BL-50 Wei Cang used for?

BL-50 is used for abdominal distension, pain in the epigastric region and back, and indigestion in infants. Our own indication record is reproduced here in full — three entries.

• Abdominal distension
• Pain in the epigastric region and back
• Infantile indigestion

The paediatric entry is what distinguishes this point. Comparing the outer-line records, BL-50 is the only one that names infants. Classical paediatric indications recur at a handful of points — our BL-63 record carries infantile convulsion — but they are uncommon, and where our data holds one this library reports it.

An honest note, and the paediatric entry needs the most care. Feeding difficulty, persistent vomiting, poor weight gain or abdominal distension in an infant requires medical assessment — infants deteriorate quickly, and a baby who is not feeding, is vomiting persistently, or has a distended or tender abdomen needs to be seen promptly. This record documents a classical indication in a historical system; it makes no claim that acupuncture treats infant digestive illness, and nothing here should delay medical care for a child. Epigastric pain that is severe or persistent requires assessment in anyone, and pain in this region can originate in the heart rather than the stomach.

How it is combined. With BL-21 Wei Shu at the same level on the inner line — the inner-and-outer pairing, and BL-21 is the Stomach’s Back-Shu point. With REN-12 Zhong Wan, the Front-Mu point of the Stomach and the Hui-Meeting point of the fu organs, in the front-and-back pairing. With ST-36 Zu San Li, the Stomach’s He-Sea point, distally. All held here.

Source: Sacred Lotus sources & references (indication record, compared against the other outer-line records; the BL-21, BL-63, REN-12 and ST-36 records queried from our own data), cross-referenced against multiple online sources.

Where is BL-50 Wei Cang located?

BL-50 is on the back, three cun out from the midline, level with the lower edge of the twelfth thoracic spinous process — the same level as BL-21 Wei Shu.

• 3 cun lateral to the midline, level with T12 — the outer Bladder line
• Level with BL-21 Wei Shu on the inner line at 1.5 cun
• BL-49 Yi She lies one level above at T11; BL-51 Huang Men one level below at L1

A useful landmark exists at this level, and it is one of the best on the lower back. The twelfth rib ends near here, and its free tip can usually be felt in the flank. It is not a precise substitute for counting, but on a stretch of back where every point is located by vertebral count it is one of the few independent references available — and it is the same structure that marks where the anatomy beneath this line changes.

Note the level our Governing Vessel records do not hold. There is no Governing Vessel point at T12, confirmed by query — DU-06 sits at T11 and DU-05 at L1. So at BL-50’s level the usual three-line arrangement across the back has only two lines, not three. Our DU-06 record sets out that gap and why it is where vertebral counting goes wrong.

Counted, not felt. The outer Bladder line has no palpable landmark of its own, so every point on it is located by counting vertebrae and measuring laterally. Miscounting moves the point into different territory while the lateral distance stays correct.

Source: Sacred Lotus sources & references (location and translation records, retained unchanged; the BL-21, BL-49, BL-51, DU-05 and DU-06 records queried, and the absence of a T12 Governing Vessel point confirmed, against our own data).

• A Manual of Acupuncture (p. 309): 3 cun lateral to the midline, level with the lower border of the spinous process of the twelfth thoracic vertebra (T12) and level with Weishu BL-21.
• Chinese Acupuncture and Moxibustion (p. 187): 3 cun lateral to the Governor Vessel, at the level of the lower border of the spinous process of the twelfth thoracic vertebra.

How is BL-50 Wei Cang needled?

Our own record states oblique insertion of 0.3–0.5 inch, with moxibustion applicable — and BL-50 sits at the level where the anatomy beneath this line changes: the pleural band above, the kidney region below. What follows is a neutral record of what the reference literature and the published measurements document. It is not instruction, and this page does not teach technique.

• Angle and depth as recorded: oblique, 0.3–0.5 inch — the same shallow oblique recorded across the thoracic outer line, and notably shallower than the 0.8–1.2 inches our record gives at BL-53 lower down.
• Moxibustion: recorded as applicable.
• Regional anatomy: latissimus dorsi and the erector spinae group overlie the point, with the lateral border of that muscle mass and the beginning of the abdominal wall musculature nearby at three cun; the twelfth rib lies in the region; the kidney lies retroperitoneally, spanning roughly the twelfth thoracic to third lumbar levels, so BL-50 is at the upper end of the kidney region; the posterior pleural recess reaches its lowest point in this vicinity.

BL-50 is one of six points measured directly by the kidney-region MRI study, and the honest limit must come with it. Abdominal enhanced T1 MRI in 61 healthy subjects measured dangerous and safe depths at BL-21, BL-22, BL-23, BL-50, BL-51 and BL-52 — so this point was measured directly, not inferred from a neighbour. Left and right did not differ significantly. Body size did: depths in the moderate-weight group exceeded those in the underweight group, and the overweight group exceeded both (P < 0.05). The authors concluded that depth may be increased for heavier patients while for underweight patients direction and depth should be restricted (Chen GT et al., Zhongguo Zhen Jiu 2022;42(9):1006–1010, PMID 36075596). Stated precisely: the paper reports the direction and significance of those differences and does not publish a single millimetre figure that can be quoted as “the safe depth at BL-50”, and none is quoted here. The usable finding is that a textbook depth describes an average body, not a constant, and the margin is narrowest in thin patients.

What is not claimed. The paediatric chest-CT study this library uses for measured pleural depths covers the outer line only as far as BL-46 — four levels above this point — and no figure from it is carried down. Our BL-45 and BL-46 records hold the two thinnest margins in that table, and they belong to those points. No case report naming BL-50 was located.

Source: Sacred Lotus sources & references (needling record, retained unchanged, and the BL-53 depth compared); PMID 36075596 (kidney-region MRI; BL-50 among the six measured points, with the no-quotable-figure limit stated); the point list of PMID 26922245 confirmed to stop at BL-46; regional anatomy from standard anatomical description.

Is there research on BL-50, and what should a reader know?

No trial isolates BL-50. Where the point appears it is one component of a digestive or back protocol, and a study that includes a point in a protocol is not evidence about that point.

The research that names BL-50 is anatomical, and its most valuable finding is a limit rather than a number. The kidney-region MRI study measured this point directly and found safe depth varies significantly with body size — narrowest in underweight subjects. It does not publish a quotable figure for BL-50, and this library does not manufacture one. A recorded depth in a textbook describes an average body; that is the finding, and it is more useful than a false precision would be.

What this page can state with confidence. BL-50 sits at T12 on the outer Bladder line, level with BL-21 Wei Shu — both names carrying wei, the stomach, which makes the inner-and-outer pairing explicit. It has the shortest action record on the outer line, a single entry. It is the only outer-line point naming infants in its indications. And it sits at the level where the anatomy beneath the line changes over: pleural considerations above, renal below.

A note on searching for it. “BL 50”, “UB 50” and “Weicang” searches return protocol trials and unrelated material matched on transliteration — and note that wei transliterates several distinct characters, so name-based searching in this region is unreliable. Our library codes this channel BL- while some sources use UB-. Any claim attached to this point should be checked against what a study actually used.

Source: Sacred Lotus sources & references (action, indication, location and translation records; the outer-line records compared against our own data); PMID 36075596 for the measured-depth finding and its stated limit.