SI-03 (Hou Xi) Back Ravine

What does SI-03 Hou Xi do?

Hou Xi SI-03 is the Shu-Stream and Wood point of the Small Intestine channel of Hand Tai Yang and the Confluent point of the Governing Vessel (Du Mai) — which makes it the tradition's principal distal point for the neck, the occiput and the whole length of the spine. Both classifications point the same way. The Nan Jing assigns the Shu-Stream point of every channel the indication "heaviness of the body and painful joints", and the Governing Vessel runs up the midline of the back from the coccyx to the head. A point that is a Shu-Stream point and the opening of the spinal vessel is, by both routes, a point for the back.

• Benefits the occiput, the neck and the back — the defining action, and the one for which SI-03 is reached for more than any other. The Small Intestine channel itself ascends the back of the arm, crosses the shoulder blade and reaches the neck and ear, so the channel route and the extraordinary-vessel route reinforce each other.
• Opens and regulates the Governing Vessel — the Confluent-point action. SI-03 is the point from the hand at which the Du Mai is reached and opened, paired in use with BL-62 Shen Mai at the foot.
• Activates the channel and alleviates pain — its channel role for stiffness and pain anywhere along the Small Intestine course: the little-finger side of the hand, the forearm, the elbow, the shoulder blade and the neck.
• Clears wind and heat, and is recorded for malaria — the classical febrile group, reflecting Tai Yang's position as the most exterior of the six channel divisions.
• Calms the spirit and is recorded for epilepsy — the Governing Vessel reaches the brain, and the spirit-and-seizure indications follow that connection rather than the Small Intestine organ.
• Clears heat and benefits the sensory orifices — the recorded use for the ear, the eye and the throat, all of which the Small Intestine channel or its branches reach.

Two of these deserve emphasis because they are what practitioners actually use the point for. The first is acute neck stiffness — the neck that will not turn — where SI-03 is the classical distal choice and is characteristically stimulated while the person slowly rotates the head, so that any change in movement shows immediately. The second is acute lumbar sprain, where the Governing-Vessel connection is the stated rationale for treating the low back from a point on the hand.

Source: Sacred Lotus sources & references (channel, Shu-Stream and Wood classification, Governing Vessel Confluent classification, and the existing action record); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 233; Chinese Acupuncture & Moxibustion, p. 167; Nan Jing (Classic of Difficulties), chapter 68, on the five-shu indications; cross-referenced against multiple online sources.

What is SI-03 Hou Xi used for?

SI-03 is used above all for the neck and the spine — acute stiff neck, occipital headache, and acute lumbar sprain — and secondarily for the ear, the throat, febrile conditions and disorders of the spirit. The indications carried in Sacred Lotus sources & references are set out below, grouped by region. They describe traditional use, not proven treatment.

• Pain and rigidity of the neck
• Stiff neck that will not rotate (acute torticollis)
• Occipital headache
• Acute lumbar sprain
• Stiffness and pain along the whole spine
• Pain in the shoulder and elbow
• Contracture and numbness of the fingers
• Tinnitus
• Deafness
• Sore throat
• Redness and pain of the eye
• Febrile disease
• Malaria, in the classical alternating chills-and-fever sense
• Night sweating
• Mania and agitated mental states
• Epilepsy

A note on what SI-03 is not for. Despite sitting on the Small Intestine channel, SI-03 is not a digestive point in ordinary use. The Small Intestine organ's functions — separating the clear from the turbid, and its paired relationship with the Heart — barely feature in this point's recorded indications. What it treats is the channel's route and the Governing Vessel it opens: the arm, the shoulder, the neck, the head and the spine. That gap between organ and channel is entirely normal in point theory and is worth stating so that a reader does not expect the point to do something the sources never claim for it.

Source: Sacred Lotus sources & references (existing indication record); Chinese Acupuncture & Moxibustion, p. 167; Deadman & Al-Khafaji, A Manual of Acupuncture, p. 233; cross-referenced against multiple online sources.

Where is SI-03 Hou Xi, and how is it used in practice?

Hou Xi sits on the little-finger side of the hand, in the substantial hollow just behind the knuckle of the little finger. The classical way of finding it is to let the hand fall into a loose fist: a transverse crease appears along the edge of the palm, and the point is at the end of that crease, on the border between the pale palm skin and the darker skin of the back of the hand — what the texts call the junction of the red and the white. Sacred Lotus sources & references hold two location records for it, one describing the end of the crease when a loose fist is made and the other describing the depression proximal to the head of the fifth metacarpal bone; they describe the same hollow from two directions and neither has been altered here.

Which points is SI-03 combined with?

• With BL-62 Shen Mai — the Confluent pair, and the single most important combination the point has. SI-03 opens the Governing Vessel from the hand and BL-62 opens the Yang Motility Vessel from the foot; the two are needled together as a matched upper-and-lower unit, and their shared territory is the inner corner of the eye, the back of the neck, the ear, the shoulder and the whole spine. The pairing is not merely a textbook convention. A latent-structure analysis of 240 passages drawn from 26 classical Chinese medical books found Shen Mai to be the most frequent partner point of Hou Xi in the entire ancient literature, ahead of LI-04 He Gu, SI-02 Qian Gu, GB-20 Feng Chi and P-05 Jian Shi; the same analysis summarised the historical Hou Xi prescriptions as working mainly to free the channels, clear heat and wind, brighten the eyes and reduce swelling and pain (PMID 35616422).
• With GB-20 Feng Chi and BL-10 Tian Zhu — the local points at the base of the skull, added to SI-03 for occipital headache and neck stiffness once the acute spasm has eased enough for the neck to be worked on directly.
• With DU-14 Da Zhui — the great meeting point of the yang channels with the Governing Vessel at the base of the neck, joining SI-03's Du Mai role to a point on the vessel itself.
• With Luo Zhen — the extra point in the hollow behind the knuckles of the index and middle fingers, the other hand point used for acute stiff neck. The two are the standard hand pair for that complaint, and the one clinical study of Luo Zhen needled both together.
• With BL-40 Wei Zhong and DU-26 Shui Gou — the other classical distal choices for acute lumbar sprain, all held in Sacred Lotus sources & references.
• With SI-19 Ting Gong and SJ-17 Yi Feng — for the ear indications, joining the distal Small Intestine point to the local points in front of and behind the ear.
• Among its category peers — every channel has a Shu-Stream point, and on the yang channels they are the Wood points. SI-03 is also, by the mother-child rule, the tonification point of the Small Intestine channel: the Small Intestine is a yang Fire channel, Wood is the mother of Fire, so the Wood point is where the channel is reinforced. Its opposite number, the sedation point, is SI-08 Xiao Hai, the He-Sea and Earth point at the elbow.

Why is the neck moved while SI-03 is treated?

Because the point is judged on movement. The reference literature describes SI-03 as a distal point stimulated while the person slowly turns the head from side to side, so that any change in the available range of rotation appears while they are still in the chair. The same approach is described for Luo Zhen and for the classical low-back points, and it explains why SI-03 has kept its reputation for the acutely seized neck: the effect, when it comes, is immediate and visible rather than something to be judged days later.

Source: Sacred Lotus sources & references (both location records, point categories, and the BL-62, GB-20, BL-10, DU-14, DU-26, BL-40, SI-08, SI-19, SJ-17 and Luo Zhen records); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 233; Chinese Acupuncture & Moxibustion, p. 167; PubMed PMID 35616422; cross-referenced against multiple online sources.

Where is SI-03 located?

• A Manual of Acupuncture (p. 233): On the ulnar border of the hand, in the substantial depression proximal to the head of the fifth metacarpal bone.
• Chinese Acupuncture and Moxibustion (p. 167): When a loose fist is made, the point is on the ulnar end of the distal palmar crease, proximal to the 5th metacarpophalangeal joint, at the end of the transverse crease and the junction of the red and white skin.

How is SI-03 Hou Xi needled in the textbooks?

Reference record only — this sets out what the standard texts document, not instruction for a reader. Sacred Lotus sources & references record perpendicular insertion of 0.5 to 0.7 inch at SI-03, with moxibustion noted as applicable. Deadman & Al-Khafaji record a comparable perpendicular range, and additionally describe insertion directed across the palm toward LI-04 He Gu, which is the deeper transverse variant used where a stronger sensation is wanted.

• Angle documented: perpendicular into the hollow at the end of the palmar crease; a transverse variant directed toward LI-04 is also recorded.
• Depth documented: approximately 0.5 to 1 cun, depending on which of the two recorded angles is followed.
• Moxibustion: documented as applicable.
• Side documented: the reference literature records treatment on the affected side for one-sided neck complaints, and the contralateral side is also described — a modern randomised trial protocol was built specifically around contralateral needling at SI-03 combined with active exercise for acute lumbar sprain (PMID 38887384).
• Accompanying movement: slow active rotation of the neck during stimulation is documented as standard practice at this point.

Safety reference — the measured anatomy. SI-03 lies on the ulnar border of the hand and carries no cavity or organ hazard of any kind: it is as far from the chest, abdomen and skull as a point can be, and none of the pneumothorax caution that governs points over the thorax and upper back applies here. What bounds it is entirely local. Immediately deep to the skin lie the abductor digiti minimi and the other small muscles of the hypothenar eminence, with the shaft of the fifth metacarpal bone as the floor. The dorsal branch of the ulnar nerve and the dorsal digital vessels of the little finger run close to the point, so a sharp radiating sensation along the ulnar border of the hand and superficial bruising are the ordinarily documented occurrences. The point is characteristically tender.

One published measurement is worth recording precisely because it concerns depth. A musculoskeletal-ultrasound validation study examined the anatomical structures lying within the documented insertion-depth ranges of the five-phase points and identified a group of points at which needles need to be inserted carefully because a vessel, nerve or joint structure lies within the stated range. SI-03 was in that group, alongside ST-36, ST-41, LU-09, KI-03, GB-34, LIV-03 and others (Complement Ther Med 2013;21(6):641–8, PMID 24280473). That is a statement about anatomy, not a report of harm: no injury occurred in the study, and the finding is that the recorded depths deserve respect rather than that the point is hazardous. Standard clean-needle practice applies. Acupuncture is carried out only by a qualified, licensed practitioner; this record documents the literature and is not a technique guide.

Pregnancy. Our sources record no pregnancy contraindication for SI-03. That caution attaches to LI-04 He Gu, SP-06 San Yin Jiao, GB-21 Jian Jing and the lower-abdominal and sacral points, and it should not be transferred to this point by assumption.

Source: Sacred Lotus sources & references (existing needling record); Chinese Acupuncture & Moxibustion, p. 167; Deadman & Al-Khafaji, A Manual of Acupuncture, p. 233 (surface and deep anatomy of the ulnar border of the hand); PubMed PMID 24280473, 38887384 — each verified resolvable and checked for retraction status before citation.

What does the name Hou Xi mean?

Hou Xi means "Back Ravine" — hou, behind or to the rear, and xi, a mountain stream or the ravine it runs in. The image is topographical and precise. When the hand closes into a loose fist, the flesh at the edge of the palm rises into a ridge and the point sits in the small gully behind it, exactly where a stream would run between two slopes. The name also completes a pair: the point immediately distal to it, SI-02 Qian Gu, is "Front Valley", and the two sit either side of the knuckle of the little finger — the front valley before the joint, the back ravine behind it. The point is also rendered "Back Stream" or "Posterior Ravine" in some translations; all describe the same hollow. Xi is a common element in point names for exactly this reason — KI-03 Tai Xi ("Great Ravine") and ST-41 Jie Xi ("Ravine Divide"), both held in Sacred Lotus sources & references, use it for the same kind of depression between raised structures.

Why does the Shu-Stream classification matter at SI-03?

The five-shu points run from the tip of each limb inward, and the classics attach a stage in the flow of channel qi to each: Jing-Well where it begins, Ying-Spring where it glides, Shu-Stream where it pours, Jing-River where it flows freely, He-Sea where it enters the deep. The Nan Jing assigns each an indication, and the Shu-Stream point's is heaviness of the body and painful joints. That single line explains most of SI-03's clinical territory: a stiff, heavy, aching neck and back is precisely the presentation the Shu-Stream point is designated for.

The element assignment adds a second layer. On yang channels the Shu-Stream point is a Wood point; the Small Intestine is a yang Fire channel, and Wood is the mother of Fire — so by the mother-child rule SI-03 is the tonification point of the Small Intestine channel. Sacred Lotus sources & references record its classification as Shu-Stream & Wood. The channel's other five-shu points held here complete the set: SI-01 Shao Ze (Jing-Well, Metal) at the little-finger nail, SI-02 Qian Gu (Ying-Spring, Water), SI-05 Yang Gu (Jing-River, Fire) at the wrist and SI-08 Xiao Hai (He-Sea, Earth) at the elbow, with SI-04 Wan Gu as the channel's Source point.

What are the eight Confluent points, and where does SI-03 sit among them?

Sacred Lotus sources & references hold all eight Confluent points of the extraordinary vessels, in their four traditional pairs, and SI-03 is the point that opens the Governing Vessel. The eight Confluent points (ba mai jiao hui xue) are the points on the ordinary channels at which the eight extraordinary vessels can be reached. Each is paired with one other — always one point on the arm and one on the leg — and each pair commands a defined region:

• SI-03 Hou Xi (Governing Vessel) with BL-62 Shen Mai (Yang Motility Vessel) — the inner corner of the eye, the neck and occiput, the ear, the shoulder, the spine and the back. This pair.
• SJ-05 Wai Guan (Yang Linking Vessel) with GB-41 Zu Lin Qi (Girdling Vessel) — the outer corner of the eye, the cheek, behind the ear, the neck and the shoulder.
• P-06 Nei Guan (Yin Linking Vessel) with SP-04 Gong Sun (Penetrating Vessel) — the heart, the chest and the stomach.
• LU-07 Lie Que (Conception Vessel) with KI-06 Zhao Hai (Yin Motility Vessel) — the throat, the chest, the lung and the diaphragm.

Four of the eight — LU-07, P-06, SJ-05 and SP-04 — are Connecting (Luo) points as well and so appear on two classification lists at once; SI-03, BL-62, GB-41 and KI-06 are not. The system was set out in Dou Hanqing's Zhen Jing Zhi Nan in the Yuan dynasty and later elaborated into the Ling Gui Ba Fa, the Mystical Turtle Eight Methods, in which the eight points are opened according to the day and hour of treatment. That framework remains in clinical use: a case report of oculomotor nerve palsy describes a treatment built on the Ling Gui Ba Fa opening of all eight, Hou Xi among them (PMID 41558712).

What is the Governing Vessel, and why does SI-03 open it?

The Du Mai — Governing Vessel, or Governor — is the yang midline vessel of the body. Its described course begins in the lower abdomen, emerges at the perineum, ascends the midline of the back through every vertebra, enters the brain at the nape, crosses the vertex and ends inside the upper lip. Because it runs through the whole spine and reaches the brain, the vessel's clinical territory is the back, the head, and the mind: spinal stiffness and pain, opisthotonos, headache, epilepsy and disorders of consciousness. It is described as the "sea of the yang channels", meeting all six yang channels of the body — which is where a point on the yang Small Intestine channel gets its access to it. That the Small Intestine channel is Hand Tai Yang, the most exterior and most posterior of the yang divisions, is the traditional explanation for why SI-03 rather than some other yang-channel point became the Du Mai's key.

Is there research on SI-03 Hou Xi?

SI-03 is among the better-studied individual points in acupuncture, and unusually the research has clustered on the two things the classical literature says it is for: acute lumbar sprain and acute neck pain. The evidence is nevertheless limited — mostly Chinese-language trials with weak blinding and generous "effective rate" outcomes — and none of it establishes clinical effectiveness. What follows is what genuinely names the point.

• Acute lumbar sprain, the largest trial. Three hundred patients with acute lumbar sprain were randomised to electroacupuncture at SI-03 alone or to an oral anti-inflammatory drug. The acupuncture arm reported higher effective rates at both seven days and one month (97.3% against 89.2%, and 99.3% against 93.2%) (Zhongguo Zhen Jiu 2007;27(1):3–5, PMID 17378192). Its value is that it tested SI-03 on its own — rare in this literature — but "effective rate" is a soft composite outcome, there was no sham arm, and the comparison of a hands-on procedure with a tablet cannot be blinded.
• Acute lumbar sprain, the point-comparison trial — and the honest result. One hundred and fifty patients all received the same massage, then were randomised to needling at one of five different distal points: the extra point Yao Tong Xue, SI-03, BL-40 Wei Zhong, BL-57 Cheng Shan or DU-26 Shui Gou. Every arm improved on pain score, lumbar movement and cure rate — but the differences between the five points were not statistically significant, and the authors concluded that any sufficiently tender distal point, strongly enough stimulated, produced comparable results (Zhongguo Zhen Jiu 2015;35(5):453–7, PMID 26255517). This is a finding worth recording plainly: it supports distal needling for acute lumbar sprain, and it does not support SI-03 being special among the distal points used for it.
• Acute neck pain — a protocol, and the caveat that goes with it. A two-group assessor-blinded pilot randomised trial was designed specifically around acupuncture at SI-03 for acute neck pain caused by stiff neck, with 36 participants, massage as the control, and the Northwick Park Neck Pain Questionnaire as the primary outcome (BMJ Open 2014;4(12):e006236, PMID 25537784). It is cited here as a study protocol; the design shows that the point's classical neck indication has been taken seriously enough to be trialled, and that is all it shows.
• Acute lumbar sprain, contralateral needling — also a protocol. A sham-controlled randomised trial of contralateral acupuncture at SI-03 combined with active exercise, with 118 planned participants and pain at ten minutes as the primary outcome, has been registered and published as a protocol (J Pain Res 2024;17:2099–2110, PMID 38887384). Results were not available when this record was written.
• Point specificity, human. Sixty healthy volunteers had the skin temperature of the back of the neck measured by infrared thermal camera while SI-03 was needled on one hand, with LU-10 Yu Ji as a control point. Posterior neck skin temperature rose significantly during needling at SI-03 on either hand, and did not change during needling at LU-10 (Cureus 2024;16(1):e52068, PMID 38344589). A small physiological study in healthy people, but a genuinely point-specific one, and it tested exactly the distant relationship the tradition claims — a point on the hand, an effect at the neck.
• Classical prescribing, documented. The latent-structure analysis of 240 passages from 26 classical medical books described above (PMID 35616422) maps which points the historical literature actually combined with Hou Xi. It documents prescribing practice, not effect.
• Animal mechanism work. Rat models of lumbar disc herniation have used electroacupuncture at "Houxi" (SI-3) with "Huantiao" (GB-30), reporting effects on high-mobility group box 1 protein in the spinal nerve trunk (PMID 37385791) and on autophagy signalling in nucleus pulposus cells (PMID 42482577). Laboratory work in animals, and the point is used in combination — it does not transfer to human practice.

The fair summary is that SI-03 has more point-specific research behind it than almost any other extraordinary-vessel Confluent point, that the acute-lumbar-sprain work is the strongest strand, and that the one trial designed to test whether SI-03 outperformed other distal points found that it did not. The site does not claim that SI-03 treats neck pain, back pain, epilepsy or deafness.

How does SI-03 differ from the points near it?

SI-02 Qian Gu lies just distal to the knuckle rather than behind it and is the Ying-Spring and Water point — the heat-clearing member of the series, weighted toward fever, sore throat and ear heat rather than toward the spine. SI-04 Wan Gu lies further back along the same border of the hand, at the wrist, and is the Source point of the channel. SI-05 Yang Gu is at the wrist joint proper, the Jing-River and Fire point. Luo Zhen, the extra point held here, sits on the back of the hand between the second and third knuckles and shares SI-03's use for acute stiff neck — but it is on no channel, carries no category, and does one narrow job, where SI-03 reaches the entire spine. LI-04 He Gu lies across the palm in the web of the thumb and is a different channel's Source point; SI-03 is sometimes needled toward it, which is the only reason the two are mentioned together anatomically. And BL-62 Shen Mai is not a neighbour at all but SI-03's constant partner at the opposite end of the body, below the outer ankle.

Source: Sacred Lotus sources & references (name, both location records, point categories, the full eight-point Confluent set, and the SI-01, SI-02, SI-04, SI-05, SI-08, BL-62, KI-03, ST-41, LI-04 and Luo Zhen records); Deadman & Al-Khafaji, A Manual of Acupuncture, p. 233; Chinese Acupuncture & Moxibustion, p. 167; Nan Jing (Classic of Difficulties) on the five-shu indications; Zhen Jing Zhi Nan (Dou Hanqing, Yuan dynasty) for the Confluent-point system; PubMed PMID 17378192, 26255517, 25537784, 38887384, 38344589, 35616422, 37385791, 42482577, 41558712, 24280473 — each verified resolvable and checked for retraction status before citation; cross-referenced against multiple online sources.