The funny-bone nerve lies in this groove: gentle pressure only, never hard.
小海 Xiaohai
“Small Sea” · SI8
Hand Taiyang · 8 of 19 · he-sea
Where. Elbow slightly bent: in the groove between the point of the elbow and the bony knob on its inner side.
For. Elbow and arm pain, numbness down the arm.
Press. Light finger pad, one minute each arm; ease off if it tingles toward the little finger.
Caution. The funny-bone nerve lies in this groove: gentle pressure only, never hard.
小海者，土也。在肘內大骨外，去肘端五分陷者中，屈肘乃得之按 · Press with me
Six slow breaths
About a minute. Press as you breathe out, ease as you breathe in.
鄰 · Neighbouring leaves
Where Xiaohai Sits at the Inner Elbow
With the elbow slightly bent, Xiaohai occupies a soft hollow tucked between two bony landmarks at the elbow’s inner-back corner. The dataset names both plainly: the olecranon of the ulna, which is the point of the elbow that meets the table when you lean on your forearm, and the medial epicondyle of the humerus, the rounded knob standing proud along the inside of the arm. Between these two promontories runs a shallow groove, and the depression announces itself best with the elbow gently flexed, when the tissues slacken and the hollow opens. Notice what is missing from the recorded location: not a single cun measurement. Many points ask you to convert proportional units before searching; Xiaohai asks only for two bones and the gap between them, which makes it one of the friendlier locations on the body for a beginner working without a chart.
What lies beneath the fingertips here deserves a gentle introduction, because many readers know this groove intimately without ever having heard its name. It is the corridor responsible for the familiar jolt people call knocking the funny bone — a sudden tingle that leaps toward the little finger when the inner elbow takes a bump. A nerve travels through this very passage on its way from the upper arm to the hand, and professional training treats everything along that narrow street with corresponding care. Surface touch engages almost none of that depth: fingertip pressure stays in skin and superficial tissue, far shy of the structures running deeper. The practical consequence is simply proportion. Where a point sits beside a busy nerve corridor, lightness stops being a stylistic preference and becomes the entire safety system.
Channel geography completes the picture. Classical maps draw the small intestine pathway beginning at the outer corner of the little fingernail, crossing the ulnar border of the hand, passing the wrist, and climbing the back of the forearm along a remarkably straight line — the catalogue’s own entries place Zhizheng (SI7) on the line connecting Yanggu (SI5) to Xiaohai (SI8), 5 cun above the dorsal wrist crease. At the elbow, that line arrives exactly at the groove between the olecranon and the medial epicondyle, where Xiaohai stands as the channel’s eighth station of nineteen. Beyond the elbow the pathway continues up the arm toward the shoulder and eventually reaches the face, ending at Tinggong (SI19) just forward of the ear. Classical teaching grants this elbow hollow special rank among the nineteen: as the channel’s he-sea point, it is described as the reach where qi, having run narrow and quick from the fingers, gathers broad and deep like water arriving at the sea.
Finding Xiaohai by Touch: A Walkthrough
Sit comfortably and let the left arm hang loose, then bend the elbow so the forearm sits about halfway up, neither fully straight nor tightly closed. First, find the point of the elbow — the olecranon — with a fingertip; it is the bony tip that would tap the table. Second, slide the fingertip around to the inner side of the arm until it lands on the rounded knob standing near the inner elbow: the medial epicondyle. Third, settle into the groove between the two, letting the slight bend of the elbow soften everything so the hollow can be felt. Press feather-light and explore the floor of the groove slowly. Repeat the whole search with hands swapped, so the other side receives exactly the same patient attention.
A few quiet confirmations help before any real pressing begins. Slowly open and close the elbow a few degrees and feel the hollow fill and deepen — the true site changes character with the movement, while bare bone never does. Compare sides with the lightest possible touch; the genuine spot often carries a hint more dull awareness than the skin a finger-width away. Expect, too, the possibility of a faint tingle glancing toward the little finger, because of the neighbour travelling through the groove; if that sensation ever turns sharp or electric, it is the signal to move off and let the area rest rather than an invitation to press harder. Calibrate against texture throughout: dense springy muscle means you have slid out of the groove, and bare bone means you are sitting on one of the promontories themselves.
Three classic slips account for most missed finds. Searching with the arm locked straight hides the groove under tension, so keep a soft bend in the elbow from start to finish. Wandering toward the crease at the front of the elbow strays into different territory altogether — the heart channel keeps its own points there, including a sea of its own — while Xiaohai holds the inner-back corner behind the knob. And hunting with force numbs precisely the sensitivity the search depends on, so explore with the weight of a coin rather than the push of a thumb. Whenever the picture muddles, return to the two landmarks, name them silently — tip, knob — and walk the short distance between them again.
Reading the Name: Small Sea
The name is a landscape sketched in two characters. Xiao 小 means small, and hai 海 means sea — together, the Small Sea. On any anatomical chart the image explains itself: the hollow between two bony promontories reads like a miniature bay, and with the elbow bent the surrounding muscles swell like land enclosing gathered water. Classical naming loved casting the body as terrain — wells, valleys, markets, pools, seas — and this elbow groove joined that geography as a modest bay granted an oceanic title. The scale word matters as much as the water word. Tradition consistently pairs grandeur with humility, and a “small sea” suggests something contained, approachable, close to home — which suits a hollow barely large enough to cradle a fingertip.
The watery imagery is theory, not decoration. Classical teaching arranges certain points below the elbow and knee into a graded sequence likened to waters maturing downstream — wellspring, spring, stream, river, and finally the he-sea point, where the current is said to pool widest and deepest. As the small intestine channel’s he-sea point, Xiaohai holds the estuary at the bottom of that cascade. Five-phase teaching adds a further layer: the he-sea points of the yang channels of the limbs all belong to the earth phase, and earth follows fire in the generating cycle. Since tradition assigns the small intestine itself to fire, commentators read this earth-phased sea as the place where the channel’s fire hands its fullness over to earth — the picture of a hot current cooling and settling as it reaches calm water.
One resonance completes the reading. The heart channel — the small intestine’s interior partner in classical pairing — keeps a he-sea point of its own just around the elbow’s corner: Shaohai (HT3), the Lesser Sea, whose second character is the same hai. Two seas face each other across one elbow, one named lesser and one named small, belonging to paired channels that classical thought treated as an interior-exterior couple. Pinyin renders today’s point Xiǎohǎi, with a dipping third tone on xiao and the same dipping third tone on hai; spoken together in flowing speech, the first syllable rises — a shift Mandarin speakers manage without thinking. The hanzi pair 小海 is spare enough to memorise at a glance, and like every terrain-named point, the name doubles as a locating hint: look for water between headlands.
Traditional Indications, Explained
Read plainly, the recorded indications number four: pain and numbness of the elbow and arm, epilepsy, gum inflammation, and cervical scrofula. The first entry carries the clearest logic. The point sits mid-route on a pathway serving the whole limb, and the old records repeatedly grouped aching, numb, heavy feelings along the arm’s course as matters for points along that course — numbness being understood in the tradition as qi and blood failing to arrive and move freely, a frame readers meet throughout classical case literature. An elbow hollow where the channel gathers was therefore a natural station in discussions of complaints anywhere downstream of the shoulder, and classical texts describe the he-sea points generally as reservoirs practitioners drew on for disorders of their own channel’s territory.
The remaining entries deserve honest handling, because their modern sound does not match their historical sense. Epilepsy in the old records covered convulsive episodes of many descriptions, filed under names that predate modern neurology entirely; today seizures belong under physician-led diagnosis and continuing medical care, and no self-care routine belongs anywhere near that conversation except as a complement discussed with one’s doctor. Gum inflammation similarly translates an era when mouth troubles were managed topically alongside general measures; anyone with swollen, bleeding, or painful gums needs dental assessment, not a pressure practice. Cervical scrofula is the archaic name for knotted swellings of the neck’s lymph glands, a condition bound to history; anyone who discovers such swellings today should seek medical evaluation promptly, without detour through self-care.
Everything on this page’s list is offered as cultural and historical record, not as evidence-backed promise. Where modern research touches self-applied pressure at all, reviews suggest effects are modest and context-dependent, and evidence tied to any single point remains thin. That honesty costs nothing and buys clarity. The tradition reasoned within its own map of channels and phases, and understanding that reasoning is interesting and worth preserving whether or not one expects results from it — so hold the history warmly, hold the safety rules firmly, and let neither substitute for the other.
Gentle Self-Care Pressing at Home
Settle in seated with the forearm supported loosely on a cushion or a table edge, elbow softly bent so the groove stays open. Locate the hollow by the walkthrough above, then rest the pad of a finger — never the tip or a knuckle — upon it. Begin with simple contact for a few slow breaths, then add small circles, letting the skin glide over the tissue rather than grinding across the groove. Pressure should register as pleasant dullness or mild warmth, nothing sharper. A common home rhythm is one to three minutes per side, once or twice daily, matched where possible to unhurried exhales so each circle rides the breath out. Then swap sides and give the other elbow its symmetrical turn, since the two grooves deserve equal courtesy.
Quality outranks duration here as everywhere in self-care. Light, patient, regularly repeated touch is the whole method; hard digging only irritates the neighbourhood and teaches the body nothing. Warm cold hands before starting, because chilled tissue guards itself. Choose a quiet corner over a screen, treating the minutes as a pause rather than a chore. People who keep the habit usually anchor it to something already in the day — morning coffee steeping, an afternoon stretch, the kettle coming to the boil — because consistency, not intensity, is what self-care traditions actually ask for. If the elbow is freshly tired after sport, long typing sessions, or carrying heavy loads, either skip the day or halve both the intention and the time.
Think of the practice as upkeep for attention rather than repair for the arm. Across weeks you may notice the elbow feeling less guarded, or the pause itself becoming the pleasant part, or perhaps nothing shifting except that a minute or two a day now go to noticing your own body. Every one of those outcomes fits the honest scope of self-acupressure. What does not fit is escalation — adding force or minutes to chase a result, especially beside a nerve corridor that answers force with complaint. Curiosity that pulls that way is best answered with a lighter hand, or by stopping altogether for the day and returning tomorrow.
Cautions and Safe Practice
Begin with the record, told straight: the licensed dataset attaches no point-specific caution to this entry, and the echoed caution list on this page is therefore empty. Emptiness describes the paperwork, not the physics. This particular hollow conducts a nerve that runs superficially through the groove, and nearly everyone has felt what a knock there produces. Gentle surface touch coexists with that neighbour comfortably; force directed into the groove invites exactly the zinging protest the funny bone is famous for, and repeated forceful work has no place in a wellness practice. So the operating principle is proportion: the smaller and busier the corridor, the lighter and briefer the touch. Lightness is not timidity here — it is the whole engineering of safe practice.
Practical rules follow from that picture. Use finger pads only — no elbows, knuckles, massage tools, or devices, and no deep probing along the groove. Skip the point over broken skin, rashes, bruising, or anywhere recently injured, injected, or operated on, and give a fresh elbow injury wide berth until ordinary activity is cleared by a clinician. During a feverish illness let the body rest instead of practising. Sharp, electric, or radiating sensations mean stopping at once — and if they linger afterwards, mention them to a clinician rather than trying again the next day. Pregnant readers, and anyone managing chronic illness, should check with a qualified practitioner before adding any new point practice to the week.
And the wider rule stands over the page: this material is educational, self-applied acupressure is comfort care, and neither diagnoses nor treats anything. Seek prompt medical attention — not more pressing — for new lumps or swellings in the neck, any seizure, gum or facial swelling that spreads or arrives with fever, an elbow that is hot, deformed, or unusable after injury, or pain that wakes you at night and refuses to settle. Persistent symptoms belong with a licensed practitioner — Western medicine or East Asian medicine, whichever suits the complaint. The small-sea imagery is charming, but the safest thing Xiaohai offers most people is a friendly, respectful acquaintance with their own elbow, handled kindly and lightly.
Xiaohai, the Small Sea, settles into the groove behind the inner knob of the elbow — the spot nearly everyone has already met as the funny bone. Classical practice reached for it when elbows ached and went numb, and tradition ranks it the small intestine channel’s gathering sea. This guide walks through finding it by touch and pressing it gently.
Self-care limits
Frequently asked
- How do I find Xiaohai without learning any measuring system?
- You hardly need one. Bend the elbow slightly, find the bony tip of the elbow, find the rounded knob on the inner side of the same elbow, and rest a fingertip in the groove between the two. The dataset’s own wording is landmark-based, so no conversions stand between you and the hollow — two promontories and a bay. If the spot hides, increase the bend slightly until the tissues slacken, then search again.
- The dataset records no caution for this point — does that mean pressing it is risk-free?
- It does not. An empty caution field tells you the licensed records contain no point-specific warning, which differs from an assurance of safety — no self-care practice is risk-free. This hollow happens to host a superficially travelling nerve, so the sensible register is gentle fingertip pressure: light touch, brief sessions, stop on sharp or electric sensation, and check with a practitioner first during pregnancy or chronic illness.
- What did classical practice use Xiaohai for?
- The traditional record lists aching and numb feelings of the elbow and arm, convulsive episodes under the old heading of epilepsy, gum inflammation, and the knotted neck swellings called scrofula. Classical texts describe it as the small intestine channel’s he-sea point where qi gathers deep, which placed it naturally in discussions along that channel. These are traditional frameworks kept for context — not evidence-backed treatment claims.
- Why do I sometimes feel a zing toward my little finger when I press there?
- Because a nerve genuinely passes through that groove — the very corridor responsible for the famous funny-bone shock. A feather-light touch may produce a faint awareness of it, which is unremarkable; a sharp or electric jolt means you have pressed enough and should move off. Treat the tingle as the groove drawing its own boundary: passed nearby, welcome; deliberately provoked, unwelcome. Nothing about acupressure requires overriding that signal.
- My elbow aches after long desk days — can pressing Xiaohai replace proper care?
- No. Self-acupressure is comfort practice, not assessment, and an aching elbow can carry many different stories, some needing professional eyes — especially after trauma, with swelling, or with numbness that persists. Enjoy gentle pressing as part of a kinder routine of breaks and movement, and let worsening or persistent symptoms prompt an actual consultation. The two belong on different shelves: daily comfort downstairs, clinical judgement upstairs.
Sources
- 01WHO Standard Acupuncture Point Locations in the Western Pacific Region (2008), World Health Organization — nomenclature conventions.
- 02A Manual of Acupuncture, Peter Deadman, Mazin Al-Khafaji and Kevin Baker — point-name tradition, he-sea theory, and channel context.
- 03aijiu-mpvue (MIT License) licensed dataset, entry for SI8 Xiaohai — location, point class, actions, and caution record.
Last reviewed
牌記This leaf, for machines
Old books ended with a colophon saying who printed them. Every leaf here carries the same facts as structured data for agents and search, with no layout in the way.
- GET /en/points/si8/leaf.json
- GET /zh-hant/points/si8/leaf.json
- GET /zh-cn/points/si8/leaf.json
- /llms.txt — the index of every leaf
- JSON-LD in the page: MedicalWebPage, MedicalEntity and FAQPage
{
"id": "SI8",
"name": {
"en": "Xiaohai",
"gloss": "Small Sea",
"zh-Hant": "小海",
"zh-Hans": "小海"
},
"channel": {
"id": "SI",
"order": 8,
"of": 19
},
"location": {
"text": "Elbow slightly bent: in the groove between the point of the elbow and the bony knob on its inner side."
},
"for": [
"elbow and arm pain",
"numbness down the arm"
],
"press": {
"text": "Light finger pad, one minute each arm; ease off if it tingles toward the little finger.",
"seconds": 60,
"sides": "both"
},
"cautions": [
"The funny-bone nerve lies in this groove: gentle pressure only, never hard."
],
"source": "Zhenjiu Jiayi Jing, book 3",
"url": "https://acupoints.com/en/points/si8",
"lastReviewed": "2026-08-24"
}