A clearing point on the forearm, Sidu (SJ-9) opens what is blocked — in the channels, in the sensory orifices, and in the flow of the arm. Its name speaks of rivers, and like rivers it moves what has stagnated.
Contraindications
Classical texts listed SJ-9 as forbidden to needle. In modern clinical use it is needled perpendicularly at standard depth; follow clean technique and stay within the stated depth range.
Name & story
The name 四渎 Sidu means "Four Ditches" or "Four Rivers". In ancient China, the four great rivers were seen as the channels through which the land was drained and kept alive. This point carries the same image: it opens and drains, clearing obstructions in the channels just as rivers clear the land. "Four" also echoes the San Jiao's role in governing the three body cavities — and beyond, reaching upward to the sensory orifices of the head.
Point family & character
SJ-9 belongs to the San Jiao channel (SJ). The sources note that this point was classically forbidden to needle in older texts — a distinction worth knowing, though in modern clinical practice it is used with standard perpendicular needling.
Location
On the lateral side of the forearm, 5 Cun below the olecranon (the bony tip of the elbow), between the radius and the ulna.
Anatomy & fascia
The point lies on the lateral side of the forearm, between the radius and the ulna.
Needling
The needle is inserted perpendicularly.
Safe depth
0.5–1.0 Cun.
Functions
Clears the channels and sensory orifices; Relieves pain in the arm and forearm; Addresses deafness and disorders of the ear; Calms seizures.
Indications
Deafness and ear disorders. Pain in the arm and forearm that restricts movement. Seizures. The point has also been noted for its use in pain along the San Jiao channel pathway.
Clinical spotlight
SJ-9 is a less commonly discussed point on the San Jiao channel (SJ), sandwiched between the better-known Sanyangluo SJ-8 and Zhigou SJ-6. Its traditional name — "Four Rivers" — hints at its clearing, draining nature. Interestingly, older classical sources listed it as forbidden to needle, which gives it a curious historical status. In modern practice it is used in a straightforward way for arm pain and sensory orifice disorders, particularly deafness.
The golden tip
If you experience tension or aching along the outer forearm, gentle self-massage along the San Jiao channel between the elbow and wrist — including the area of SJ-9, roughly midway down the forearm on its outer side — can help ease discomfort. Press with a thumb and hold for 30–60 seconds, breathing slowly.
For education only — not medical advice. Consult a qualified practitioner.