The He-Sea point of the Small Intestine channel — Xiaohai (SI-8) sits in the groove at the elbow, clearing Heat, calming the Shen and easing pain along the channel. A quieter, more specialised point than the great tonics, it shines in neurological disorders, swellings and mental agitation.
Name & story
The name 小海 Xiaohai is best read as "Small Intestine Sea" rather than simply "Small Sea" — the character 小 (Xiǎo) here stands for 小肠 Xiǎo Cháng, meaning Small Intestine. A He-Sea point is where the Qi of the channel gathers and deepens, like a river finally reaching the sea. So Xiaohai is the place where the energy of the Small Intestine channel — having travelled the whole length of the arm — arrives, spreads out, and settles. The image is of a small but real sea: contained, calm, and deep.
Point family & character
Xiaohai (SI-8) belongs to the Small Intestine Meridian (SI). In character it is the He-Sea point and the Earth point of the channel — which makes it the sedation point of the Small Intestine channel. As the He-Sea point, it is traditionally indicated for counterflow and disorders that reflect the channel's depth.
Five-element dynamics
The Small Intestine channel belongs to the Fire element, and yet Xiaohai is its Earth point — Earth within Fire. In the five-element sequence, Earth is the child of Fire, the stage where Fire's energy begins to settle and consolidate. This gives the point a natural capacity to sedate and calm: when the Fire of the Small Intestine channel blazes too strongly — in the form of Heat, agitation or swelling — the Earth point draws it downward and quiets it. It also connects, through the channel's paired relationship, to the Heart, helping settle the Shen when the Heart's Fire is disturbed.
Location
Find the inner side of the elbow and locate the two bony prominences: the rounded tip of the olecranon (the point of the elbow) and the medial epicondyle (the bony bump on the inner side of the humerus). Xiaohai (SI-8) sits in the depression between these two landmarks. You may recognise it as the spot that gives a distinctive tingling sensation when accidentally knocked — popularly known as the "funny bone" — because the ulnar nerve runs just here.
Anatomy & fascia
The point lies in the depression between the tip of the olecranon process of the ulna and the tip of the medial epicondyle of the humerus — the bony groove on the inner side of the elbow. The ulnar nerve runs deep to this point.
Needling
The needle may be inserted obliquely, either toward the wrist or toward the shoulder (distal or proximal), or perpendicularly (straight in).
Safe depth
Oblique insertion: 0.5–1 Cun. Perpendicular insertion: 0.3–0.5 Cun.
Moxa, cupping & Tui Na
Acupressure on this point can help relieve local elbow pain and tension. Gentle massage in the groove between the two bony landmarks is accessible at home. Moxa may be used with care, keeping warmth at a comfortable level given the sensitivity of the area.
Functions
Clears Heat and dissipates swelling. Calms the Shen. Activates the channel and alleviates pain. Dispels Wind. Clears Damp Heat. Expels Tai Yang channel pathogenic Qi. Invigorates the collaterals and relaxes the muscles.
Indications
Scrofula (swollen lymph nodes of the neck), swelling and pain of the throat. Pain and contraction of the elbow; ulnar nerve neuralgia or paralysis. Pain of the scapula and shoulder. Swelling of the cheek and submandibular region. Pain of the gums. Epilepsy and epileptic convulsions. Trembling, chorea (including Huntington's chorea). Psychosis and mad walking. Agitation, inability to sleep. Constipation. In classical use, intestinal spasms and pain below the umbilicus.
Mind & spirit (Shen)
One of the quieter but real uses of Xiaohai (SI-8) is in calming the troubled mind. Through the paired relationship of the Small Intestine channel with the Heart, this point can reach the Shen — particularly when the Heart is disturbed by Heat. The old texts list epilepsy, tongue thrusting, mad walking, agitation of the Heart, and an inability to sleep as indications. When Fire runs wild in the channel and the Shen loses its anchoring, Xiaohai offers a steadying hand — not by nourishing, but by clearing and settling, the way a sea absorbs the turbulence of a storm.
Point combinations
With Houxi SI-3, Zanzhu BL-2 for epileptic convulsions, mad walking and agitation of the Heart (classical formula). With Jiaosun SJ-20 for pain of the gums (Great Compendium). With Chize LU-5, Jianyu LI-15, Jianshi P-5, Daling P-7, Houxi SI-3 and Yuji LU-10 for contraction of the elbow (Great Compendium). For disorders of the Small Intestine itself, the sources advise pairing with Xiajuxu ST-39 (the lower He-Sea of the Small Intestine) or Xiaochangshu BL-27 (its back-Shu point), which have a more direct action on the organ.
Clinical spotlight
There is a striking paradox at Xiaohai (SI-8): despite being the He-Sea point of the Small Intestine channel, it has relatively little action on the Small Intestine organ itself. As Deadman explains, this is because the Small Intestine is located in the lower body, while its channel runs along the upper limb — so the channel's own points have less reach to the organ than one might expect. Clinicians therefore turn to ST-39 or BL-27 for digestive Small Intestine disorders. What Xiaohai excels in instead is neurological and psychiatric presentations — epilepsy, trembling, psychosis — and local conditions: elbow pain, ulnar nerve problems, scrofula and throat swellings. Its role as the Earth (sedation) point of a Fire channel makes it a natural choice for clearing excess and calming, rather than tonifying.
The golden tip
The point is easy to find at the inner elbow, in the groove between the two bony bumps. Gentle pressure here — with a fingertip, held for one to two minutes — can help ease local elbow discomfort or tension along the inner arm. Because the ulnar nerve runs nearby, the sensation can be quite strong; press gently rather than firmly, and never with sharp or prolonged force.
For education only — not medical advice. Consult a qualified practitioner.