Triple Energizer MeridianTE9

Sidu 四瀆

For reference only · not a substitute for diagnosis or treatment

Short answer

Back of the forearm, 5 cun below the point of the elbow (tip of the olecranon), midway across the gap between the radius and the ulna.

See it in 3DRotate the body and peel back the skin to see the bones and muscles beneath.
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🖼See it in pictures

Sidu — ① Where on the body? — **① Where on the body?**

Sidu — Textbook view — skin on the left, muscle and bone underneath on the right — **Textbook view — skin on the left, muscle and bone underneath on the right**
Location and structures come from our 3D model; only the drawing style was refined with AI. Labels are added by us.

Sidu — ③ Under the skin — **③ Under the skin**
Radius · Ulna · Supinator

Rendered straight from the 3D model at the computed location. The glowing ring marks Sidu.

On this page

Where is Sidu?
How do I find it on my body?
Before you press
How has it been used traditionally?
FAQ

1Where is Sidu?

Back of the forearm, 5 cun below the point of the elbow (tip of the olecranon), midway across the gap between the radius and the ulna.

Beneath the point

Radius · Ulna · Supinator

Our 3D measurement · In our 3D model: 5 cun (107.4 mm) below the tip of the olecranon, on the back skin midway between the radius and ulna.

2How do I find it on my body?

Find the point of the elbow (tip of the olecranon).
Go 5 cun toward the wrist (five twelfths of the 12-cun forearm span).
Press into the hollow between the radius and the ulna.

Check · taking the elbow tip as level with the elbow crease, it is about 7 cun above the wrist crease.

What is a “cun”?

A cun is a body-scaled unit of length. The precise way is to divide a bone length into equal parts (proportional bone cun); finger widths are a quick estimate.

📖 Words explained

wrist crease: The horizontal crease that forms at the wrist when it is slightly bent. There is one on the palm side and one on the back, and they are starting lines for measuring arm points.

3Before you press

⚠ Do not press when

Avoid broken or swollen skin and press only to a comfortable level.
Acupressure is not a substitute for medical care.

4How has it been used traditionally?

A point of the Triple Energizer meridian on the back of the forearm; the name means 'four rivers'.

From traditional texts — not a claim of effect.

?FAQ

Where exactly is Sidu?

Back of the forearm, 5 cun below the point of the elbow (tip of the olecranon), midway across the gap between the radius and the ulna.

How do I find Sidu?

Find the point of the elbow (tip of the olecranon). Go 5 cun toward the wrist (five twelfths of the 12-cun forearm span). Press into the hollow between the radius and the ulna. taking the elbow tip as level with the elbow crease, it is about 7 cun above the wrist crease.

What should I watch out for?

Avoid broken or swollen skin and press only to a comfortable level. Acupressure is not a substitute for medical care.

← PreviousSanyangluo · TE8 Next →Tianjing · TE10

Sources

Location: WHO Standard Acupuncture Point Locations in the Western Pacific Region (2008), p. 162
Standard comparison: Chinese national standard GB/T 12346-2021 (Nomenclature and location of meridian points), p. 23
Korean anatomical terms: KMLE medical dictionary (Korean Medical Association terms)
Classification and traditional-use cross-check: AcuAtlas dataset (CC BY 4.0)

Positions computed from the WHO standard locations (2008) on Z-Anatomy (CC BY-SA 4.0) · BodyParts3D © DBCLS. For reference only — not a substitute for diagnosis or treatment. See a clinician if you are unwell.