BL-66 (Tong Gu) Valley Passage

What does BL-66 Tong Gu do?

BL-66 is the Ying-Spring and Water point of the Bladder channel — and because the Bladder is itself a yang WATER channel, BL-66 is its HORARY point, the element matching its own channel. Our record gives it two actions, both directed upwards.

• Clears the head — the distal action of a point at the far end of the longest channel in the body
• Descends Lung and Stomach qi — the rebellious-qi action, which is what the nosebleed indication rests on

Horary is not sedation, and this is where that trap sits on the Bladder channel. A horary point shares its channel’s element; a sedation point carries the channel’s child element. Derived from our own element records the Bladder series runs BL-67 Metal, BL-66 Water, BL-65 Wood, BL-60 Fire, BL-40 Earth — so:

• Horary point — BL-66 Tong Gu (Water on a Water channel) — this point
• Sedation (child) point — BL-65 Shu Gu (Wood, the child of Water), half an inch away
• Tonification (mother) point — BL-67 Zhi Yin (Metal generates Water)

Our P-08 record flags the identical confusion on the Pericardium channel, where the horary point is likewise mistaken for the sedation point. The two roles being adjacent points here makes the error especially easy.

Source: Sacred Lotus sources & references (channel, element and action records; the full Bladder five-shu series queried and verified against our own data, and the P-08 horary note), cross-referenced against multiple online sources.

What is BL-66 Tong Gu used for?

BL-66 is used for headache, neck rigidity and blurred vision, for nosebleed, and for mania. Our own indication record is reproduced here in full.

• Headache
• Neck rigidity
• Blurring of vision
• Epistaxis (nosebleed)
• Mania

Nosebleed is the entry that distinguishes this point from its neighbour, and it follows directly from the recorded action of descending rebellious qi. The Bladder channel begins at the inner canthus of the eye and its first points sit beside the nose, so a distal point on the same channel carrying a nasal indication is the channel’s own logic rather than a stray entry.

The overlap with BL-65, stated plainly. Four of BL-66’s five indications — headache, neck rigidity, blurred vision and mania — are identical to entries on our BL-65 Shu Gu record, a point half an inch proximal. That duplication is real in the source material. What separates the two is the five-shu role: BL-66 is the horary point, BL-65 the sedation point. This library discloses the overlap rather than differentiating the lists artificially.

An honest note. Mania requires medical diagnosis and management, and the term here reflects a classical category rather than a modern diagnosis. Sudden severe headache with neck rigidity requires urgent medical assessment. A nosebleed that will not stop, or one that is heavy or recurrent, needs medical care. This record describes classical use and should not delay any of that.

How it is combined. With BL-67 Zhi Yin at the nail corner and BL-65 Shu Gu proximal — three five-shu points within an inch. With LI-20 Ying Xiang and DU-23 Shang Xing for the nose. With BL-10 Tian Zhu for the neck. All held here.

Source: Sacred Lotus sources & references (indication and action records; the BL-65, BL-67, BL-10, LI-20 and DU-23 records queried from our own data), cross-referenced against multiple online sources.

Where is BL-66 Tong Gu located, and is there another point with this name?

BL-66 is on the outer edge of the foot, in the hollow just in front of and below the joint at the base of the little toe. And yes — there is a second Tong Gu, which is worth knowing before searching for either.

• Anterior and inferior to the fifth metatarsophalangeal joint, on the lateral side of the foot
• BL-65 Shu Gu lies just proximal, on the other side of the same joint; BL-67 Zhi Yin is at the little-toe nail corner

A genuine name collision in this library. KI-20 is also called Tong Gu — on the abdomen, on the Kidney channel, five cun above the navel. Same pinyin, entirely different point. The two are distinguished in the literature as Zu Tong Gu (foot) and Fu Tong Gu (abdomen), and a reader working from pinyin alone can land on the wrong one. This library records several such collisions, including the Shen Men and Tian Jing cases noted on their own pages.

On the name. “Tong Gu” means Valley Passage — the valley being the depression beside the joint, and tong the sense of passing through. Positional, like its neighbour BL-65 Shu Gu (Bundle Bone), which is named for the bone on the other side of the same joint.

Source: Sacred Lotus sources & references (location and translation records, retained unchanged; the KI-20 record and the other name-collision records queried from our own data).

• A Manual of Acupuncture (p. 324): On the lateral side of the foot, in the depression anterior and inferior to the fifth metatarsophalangeal joint.
• Chinese Acupuncture and Moxibustion (p. 190): Anterior to the fifth metatarsophalangeal joint, at the junction of the red and white skin.

How is BL-66 Tong Gu needled?

The standard texts record perpendicular insertion to roughly 0.2–0.3 inch, with moxibustion applicable — shallower than its neighbour BL-65. What follows is a neutral record of what the reference literature documents, not instruction for a reader.

• Angle and depth as recorded: perpendicular, 0.2–0.3 inch.
• Shallower than BL-65, which our record gives as 0.3–0.5 inch. Half an inch further along the foot the tissue is thinner, and the recorded depths track that.
• Moxibustion: recorded as applicable.
• Regional anatomy: the lateral border of the fifth toe’s base; dorsal digital branches of the lateral plantar and superficial fibular nerves and small digital vessels run in the region; the proximal phalanx and metatarsal head lie beneath.

Hazard, stated proportionately. This is a low-hazard point: no body cavity, no major vessel, no large nerve trunk, bone immediately beneath and a recorded depth of two to three tenths of an inch.

What is not claimed. No study measuring a safe depth at BL-66 could be located, and none is borrowed. The paediatric chest-CT study this library uses for measured depths covers 23 named points on the trunk and does not reach the foot. No case report naming BL-66 was located, and none is asserted.

Source: Sacred Lotus sources & references (needling record, retained unchanged, and BL-65's recorded depth queried for comparison; the point list of PMID 26922245 / PMC4769822 confirmed not to include BL-66), cross-referenced against multiple online sources; regional anatomy from standard anatomical description.

Is there research on BL-66, and what should a reader know?

No trial isolates BL-66. Where the point appears it is one component of a protocol, and a study that includes a point in a protocol is not evidence about that point.

The nearby point that does have a literature is BL-67, two positions along, for breech presentation — and our BL-67 record examines that evidence at length, including what it does not establish. It is evidence about BL-67. Nothing from it transfers to BL-66, and the short distance makes that worth stating.

What this page can state with confidence. BL-66 is the Water point of a yang Water channel, which makes it the horary point — not the sedation point, which is BL-65 immediately proximal. Both are derived from our own element column and both agree with BL-67 as tonification. Its indication list overlaps BL-65’s by four of five entries, with nosebleed as the distinguishing one. And it shares its name with KI-20 on the abdomen, which is the practical trap on this page.

A note on searching for it. “BL 66”, “UB 66” and “Tonggu” searches return protocol trials, the Kidney-channel point of the same name, and unrelated material — Tonggu also matches place names and a musical-instrument term. 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 (element and indication records; the Bladder five-shu series, the BL-65 and BL-67 records and the KI-20 name collision queried from our own data).