Small Intestine MeridianSI8

Xiaohai 小海

For reference only · not a substitute for diagnosis or treatment

Short answer

Back-inner elbow, in the hollow between the olecranon (elbow tip) and the humerus's medial epicondyle.

He-sea point (Earth)

See it in 3DRotate the body and peel back the skin to see the bones and muscles beneath.
Open the 3D Acupoint Map →

🖼See it in pictures

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

Xiaohai — 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.

Xiaohai — ③ Under the skin — **③ Under the skin**
Humerus · Ulna

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

On this page

Where is Xiaohai?
How do I find it on my body?
The classical posture
Before you press
How has it been used traditionally?
Classical text
FAQ

1Where is Xiaohai?

Back-inner elbow, in the hollow between the olecranon (elbow tip) and the humerus's medial epicondyle.

With the elbow slightly bent, it is the groove that carries the ulnar nerve.

Beneath the point

Humerus · Ulna

Our 3D measurement · In our 3D model: on the skin in the direction midway between the olecranon tip and the medial epicondyle (5.9 mm from the ulnar nerve).

2How do I find it on my body?

Bend the elbow slightly.
Feel the elbow tip (olecranon) and the bony bump on the inner elbow (medial epicondyle).
Press gently into the groove between them.

Check · tapping it sends a tingle toward the little finger — the 'funny bone' (ulnar nerve).

📖 Words explained

Yixue Rumen: An introductory medical book published by Li Chan in Ming China in 1575, widely read in Joseon Korea as well.
ulnar nerve: The nerve running down the inner arm to the little-finger side. It passes through a bony groove at the back of the inner elbow; bump it and you feel a jolt down to the little finger (the 'funny bone').

3The classical posture

Bend the elbow and lift the hand toward the head (the Yixue Rumen's "hand bent toward the head").
Press the groove between the elbow tip (olecranon) and the inner bony bump (medial epicondyle).
WHO 2008 and China's GB/T 12346-2021 use a slightly bent elbow; Lingshu ch. 2, by contrast, says to straighten the arm.

4Before you press

⚠ Do not press when

The ulnar nerve lies just under the skin here.
Do not press hard or rub.
Ease off at once if tingling spreads to the little finger.
Avoid broken or swollen skin and press only to a comfortable level.
Acupressure is not a substitute for medical care.

5How has it been used traditionally?

Classified as the He-sea (Earth) point of the Small Intestine meridian — a historical classification, not a claim of effect.
The name means 'small sea' — xiao here points to the Small Intestine channel. Not to be confused with HT3 (Shaohai, 少海).
The Ming-dynasty Yixue Rumen (1575) locates it with the elbow bent and the hand turned up toward the head.

From traditional texts — not a claim of effect.

6Classical text

Donguibogam (Heo Jun, 1613), Acupuncture and Moxibustion, "Xiaohai"

在肘內大骨外去肘端五分陷中《銅人》
屈手向頭取之又云屈肘得之《入門》
手太陽脈之所入爲合 …《銅人》

①Outside the large bone of the inner elbow, in the hollow five fen from the elbow tip. Tongren Shuxue Zhenjiu Tujing
②Take it with the hand bent up toward the head; another account says it is found with the elbow bent. Yixue Rumen
③Where the Hand Taiyang channel enters, which makes it the He-sea point. Tongren Shuxue Zhenjiu Tujing

Source tags as given in the Donguibogam: Tongren = Tongren Shuxue Zhenjiu Tujing (1026), Rumen = Yixue Rumen (1575).
The garbled glyph 狪 in the Wikisource text has been corrected to 肘 (elbow) in three places.
Lingshu ch.
2 says to take it with the arm straightened (伸臂), unlike the bent elbow of the Yixue Rumen.
"…" marks the needling depth and moxa count, left out because they are for licensed practitioners.

Original text as written · translation is ours.

?FAQ

Where exactly is Xiaohai?

Back-inner elbow, in the hollow between the olecranon (elbow tip) and the humerus's medial epicondyle. With the elbow slightly bent, it is the groove that carries the ulnar nerve.

How do I find Xiaohai?

Bend the elbow slightly. Feel the elbow tip (olecranon) and the bony bump on the inner elbow (medial epicondyle). Press gently into the groove between them. tapping it sends a tingle toward the little finger — the 'funny bone' (ulnar nerve).

What should I watch out for?

The ulnar nerve lies just under the skin here. Do not press hard or rub. Ease off at once if tingling spreads to the little finger. Avoid broken or swollen skin and press only to a comfortable level. Acupressure is not a substitute for medical care.

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Sources

Location: WHO Standard Acupuncture Point Locations in the Western Pacific Region (2008), p. 91
Standard comparison: Chinese national standard GB/T 12346-2021 (Nomenclature and location of meridian points), p. 15
Korean anatomical terms: KMLE medical dictionary (Korean Medical Association terms)
Classification source: Lingshu ch. 2 (Ben Shu) for the five transport points; Nanjing ch. 64 for the phases
Posture and traditional use: Hyeoljari Seodang (Bookdramang, 2015; Korean), ch. 6 "Xiaohai" and appendix (Yixue Rumen indications)
Classical text: Donguibogam, Acupuncture and Moxibustion, "Xiaohai" — Wikisource public edition (garbled glyph 狪 corrected to 肘)
Indications: Yixue Rumen vol. 1 (Wikisource)
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.