Xiaohai (SI8): The Funny-Bone Groove Point for an Aching Elbow and Forearm

Where Xiaohai Sits

This point sits at the back of the elbow, in the groove between the point of the elbow and the bony knob on its inner side. It is the place people call the funny bone.

The line it belongs to begins at the outer corner of the little fingernail. It runs along the little-finger edge of the hand and wrist, up the back of the forearm, through this groove at the elbow and up the back of the upper arm. At the shoulder it zigzags across the shoulder blade before climbing the side of the neck to the cheek and the front of the ear. Vietnamese and Chinese texts call it the Small Intestine channel. This is its eighth stop, and the only one at the elbow.

The old texts place it in the depression between the tip of the olecranon and the medial epicondyle of the humerus. The olecranon is the point of the elbow, the hard tip you lean on, at the top of the forearm bone on the little-finger side. The medial epicondyle is the bony knob on the inner side of the elbow, at the lower end of the upper arm bone. With the elbow bent, the two sit close together, and between them lies a narrow groove you can feel with a fingertip.

Underneath is the most important fact about this point: the ulnar nerve. It runs through this groove with little padding over it, which is why a knock here sends a jolt into the little finger. The nerve carries feeling to the little finger and half of the ring finger, and works many of the small muscles of the hand that make fine movements and a strong grip. Around it, the groove is lined by the start of the forearm muscle that bends the wrist toward the little-finger side (the flexor carpi ulnaris). The skin over the point is served by a branch from the eighth cervical and first thoracic roots.

Why This Spot

On the anatomical side, this groove is where the forearm muscles on the little-finger side begin, the ones that grip, carry and steady the wrist. Years of carrying bags, wringing cloths, gardening and holding tools load them. The tissue at the edges of the groove often becomes tender in people whose forearm and elbow ache after use. Because the nerve runs right through, the area is also sensitive in a way most points are not, and that shapes how you press it.

In this tradition the point is the sea point of its channel, where the flow is described as running deep, like a river entering the sea. The old books turn to it for an elbow that aches and will not bend freely, for tight, cramping muscles in the shoulder and forearm, and for pain that runs along the little-finger side of the arm. In Vietnamese practice it is commonly used for elbow and forearm pain.

Xiao means small; hai means sea. The name echoes its neighbour at the inner end of the elbow crease, called the Lesser Sea; both mark deep, sea-like places at the elbow. Its Vietnamese name, Tiểu Hải, carries the same meaning.

What the Old Texts Say About Xiaohai

The Lingshu, the Spiritual Pivot from the Han dynasty, lists the transport points of each channel in its chapter on root points. There this point is named as the sea point of the Small Intestine channel, found on the inner side of the elbow, outside the large bone, in a hollow half a body inch from its tip. That short description still matches the groove you can feel today, two thousand years later.

The Vietnamese handbook of points and channels by Ngo Trung Trieu, published by Hong Duc, lists it for cramping and tightness of the shoulder and forearm muscles, elbow pain, and pain along the nerve on the little-finger side of the arm. It also lists some complaints of the mind from older teaching. It gives a clear method for finding it: bend the elbow, and take the point in the groove between the point of the elbow and the inner bony knob of the upper arm bone. That is the method on this page.

The World Health Organization, in its 2008 standard, keeps the same landmarks. In the wider tradition, this point has always been taught with a caution, because the nerve here is so close. Teachers prefer a light touch on this point. That advice is worth more to a self-presser than any list of uses, and it rests on long experience, as does the reputation of the point for an aching elbow.

Points That Work With Xiaohai

The first partner sits at the inner end of the elbow crease. Bend the elbow fully; the crease ends near the inner bony knob, and that partner sits in the dip there, in front of the knob rather than behind it. In this tradition the two are commonly used together for an aching inner elbow and forearm.

The second sits at the outer end of the same crease, in the dip between the end of the crease and the bony knob on the outer side of the elbow. It is used with this one when the ache goes all round the elbow.

The third sits on the little-finger edge of the hand. Make a loose fist; the point is at the end of the crease that forms below the knuckle of the little finger, where the pale palm skin meets the back-of-hand skin. It sits on the same line and is used with this one when pain runs along the little-finger side of the arm and hand.

How to Find and Press Xiaohai

Getting Into Position

Sit at a table with the forearm resting on it and the elbow bent to about a right angle. Turn the palm down, or toward your body, so the inner side of the elbow faces up a little. Do not lean on the elbow. A folded towel under the forearm keeps the arm relaxed.

How to Find It

With your other hand, find the point of the elbow, the hard tip at the back. Then find the bony knob on the inner side of the elbow, the side nearest your body. Rest a fingertip between them. You will feel a narrow groove. If you press there and feel a tingle toward the little finger, you have found the nerve, and you are in the right groove.

Now probe gently with a rounded-tip pressing tool, or the tip of your thumb with the nail cut short. Stay toward the edges of the groove rather than its very floor. Move in small steps. One spot will sting: a small, sharp, pinpoint tenderness that stays under the tip. That spot is the point. Any electric tingle running into the fingers means you are on the nerve; lift off and move a little.

How to Press It

Keep the tip on the stinging spot and rub in small, light circles, about the size of a fingernail, roughly one each second. Aim the pressure gently into the groove, not hard down into its floor. Hold the forearm still with the table and your fingers. Keep the tip on the same spot; do not let it slide along the groove.

How Much Pressure

Use lighter pressure here than on almost any other point. A small sting under the tip is right. The test is what happens when you lift off: the sting should fade within moments. If the pain stays after you lift off, if it spreads, or if the area turns swollen, hot or red, stop and leave it for several days. Stop at once for any tingling or numbness running into the little finger or ring finger. If you are holding your breath, you are pressing too hard.

How Long

Work each arm for one to three minutes. In the first sessions keep to about one minute. As the days go on, add a little time, up to three minutes. Do both arms, even when only one complains. Once or twice a day is plenty. Pressing longer does not add benefit; around a nerve, it can add irritation.

When to Do It

Morning suits an elbow that is stiff on waking. Late afternoon suits the forearm ache that builds after carrying, gardening or housework. Before bed is a good time too, as part of winding down. Do not press in the middle of the night. If an aching elbow or a numb hand wakes you, pressing then tends to wake you further, and a numb hand at night is a sign to speak to your doctor, not to press.

What This Won't Do

It will not change the reason your elbow and forearm ache. Common reasons are overuse of the forearm muscles, tendon trouble at the inner bony knob, wear in the elbow joint, and a neck that irritates the nerves running to the arm. A point in this groove will not out-argue any of that. Pressing works best alongside the plain things: resting the arm after heavy tasks, not leaning on your elbows, keeping the elbow fairly straight at night, and gentle stretches for the forearm.

It will not replace a diagnosis either, and with this point that matters a great deal. Numbness or tingling in the little finger and ring finger, clumsiness with buttons, a weaker grip, or thinning of the muscle between the thumb and first finger can mean the nerve in this groove is being squeezed. That needs a doctor's check, sometimes nerve tests, and pressing on the groove may make it worse. An elbow that is suddenly hot, swollen and red, especially with a fever, needs to be seen the same day. An elbow that will not move after a fall may be broken.

Safety First

Do not press over skin that is broken, burned, infected, badly bruised or rashy. Leave the area alone with a recent fracture or sprain, after elbow surgery until your surgeon agrees, or with a swollen fluid-filled lump over the point of the elbow. Skip this point if the little finger or ring finger is already numb or weak. If you take blood thinners, bruise easily, have a bleeding disorder, or have reduced feeling in your hands, use lighter pressure, keep sessions short, and talk to your doctor first.

Stop at once if the pain stays after you lift off, spreads, or if the area becomes swollen, hot or red. Stop too for any tingling or numbness into the fingers. Nothing here requires you to push through pain. For the full list of cautions and the situations where pressing on yourself is not appropriate, read the full safety guide before you begin.

Questions People Ask

Where is the Xiaohai (SI8) pressure point? Xiaohai (SI8) sits at the back of your elbow, in the groove between the point of the elbow and the bony knob on the inner side. It is the spot people call the funny bone, where a knock sends a zing into the little finger. In English it is called the Small Sea; in Vietnamese, Tiểu Hải.

Why does pressing it make my little finger tingle? A nerve runs right through this groove, close to the skin. It carries feeling to the little finger and half of the ring finger. A firm press lands on it and sends a tingle down the arm. That is your signal to lift off, press more lightly and move to the edge of the groove. The sting you want stays under the tip.

How long should I press Xiaohai? One to three minutes on each arm, always with light pressure. Keep the first sessions to about a minute, then add a little time over the days. Once or twice a day is enough. Work both arms, even if only one aches.

My little finger and ring finger go numb. Should I press here? No. Numbness in those fingers, especially when the elbow has been bent for a long time, often means the nerve in this groove is already irritated. Pressing on it may make it worse. Let a doctor check it, and keep the elbow fairly straight at night.

Is this the same as the point on the inner end of the elbow crease? No, but they are close. That point sits on the front of the elbow, at the inner end of the crease when the elbow is bent. This one sits further back, in the groove behind the inner bony knob. They are often used together.

Can I lean on my elbow to press it? Please do not. Leaning your weight on the elbow presses hard on the nerve and is one of the common reasons it becomes irritated. Use a rounded-tip tool or your thumb tip, with light pressure you can control.

Other Points in This Library

Each of these sits within reach of the same hand. They are often worked in the same sitting.

This page shares general information about a traditional practice. It is not medical advice and does not replace what your doctor has given you. If you are pregnant, managing a health condition, or unsure whether this applies to you, check with your doctor first.

The whole inner edge of the foot, laid out on one page with photographs, is in The Foot Map — the free book. For every point in this library, see the full pressure point index.

(Point shown: SI8 · Xiaohai · Small Sea · Tiểu Hải.)