Ciliao (BL32): The Sacrum Point for an Ache at the Base of the Spine

Where Ciliao Sits

This point sits on the sacrum, the flat triangle of bone at the base of the spine, between the two buttocks. On each side of the centre line the sacrum has four small openings, one above the other, where nerves pass out to the back. This point lies over the second opening on each side. It is about halfway between the dimple low on your back and the centre line, a little lower.

It belongs to the line that Vietnamese and Chinese texts call the Bladder channel. That line begins at the inner corner of the eye, crosses the head and runs down the back in two tracks on each side of the spine. Over the sacrum, the inner track drops into the four openings, one after the other. The four points there are known as the eight crevices, four on each side. This is the thirty-second stop, the second of the four.

The old texts place it in the second sacral opening. The World Health Organization standard says the same: in the sacral region, in the second posterior sacral foramen. The foramen is the opening in the bone. You cannot see it, but you can often feel a slight hollow over it with a fingertip, especially in slimmer people. The surest guide is the pair of bony knobs at the back of the pelvis, under the two dimples. The second opening sits roughly level with their lower edge, about halfway in toward the centre line.

Under the skin lies the tough sheet of tissue that wraps the lower back and fastens to the sacrum. Beneath it are the lowest ends of the muscles that run up beside the spine, which begin here on the back of the sacrum. The skin is served by small nerves from the upper sacral roots that run out over the buttock. Deep in the opening itself, protected by the bone, a branch of the second sacral nerve passes through.

Why This Spot

On the anatomical side, the sacrum is where the spine meets the pelvis. It sits wedged between the two hip bones, joined to them by strong, stiff joints. Those joints barely move, but they take the whole weight of the upper body and pass it into the legs. When they are strained, or when the muscles that start on the sacrum are tight, the ache sits deep and low, often on one side, and is worse after sitting or on rising from a chair. People who sit a lot, or who have had a fall onto the bottom years ago, often find this area tender.

In this tradition, the eight crevices of the sacrum are a gathering place for the lower body. They sit over the pelvis, close to the organs of the lower belly, and are used for complaints of the low back, the pelvis and the passing of water. The second crevice is the most used of the four, the one teachers reach for first.

The name is plain. Ci means second, or next in order; liao means a crevice or bone hollow. Its Vietnamese name, Thứ Liêu, carries the same meaning.

What the Old Texts Say About Ciliao

The Systematic Classic of Acupuncture and Moxibustion, the Jiayi Jing, compiled by Huangfu Mi in the third century, places this point in the second hollow of the sacrum, and lists the four crevices together as a group. That grouping has stayed in every major text since.

The Vietnamese handbook of points and channels by Ngô Trung Triều, published by Hồng Đức, places it in the second opening, in the hollow beside the spine. To find it, the handbook says, go to the second sacral opening, at the midpoint between the lower edge of the bony knob at the back of the pelvis and the centre line of the spine. It lists the point for pain in the low back and the sacrum and pelvis, and for complaints of the pelvic organs, including unusual discharge.

Notice how the list follows the place. Everything on it sits in the pelvis, the bowl of bone that this point sits on from behind. Later practice also uses the crevices for painful periods, which belong to the same region.

In the wider tradition, this point is the one teachers use for the deep, low ache at the base of the spine that does not respond to rubbing the waist. Its reputation rests on long use rather than proof. It tells you where generations of practitioners found tender, useful tissue in people who sat, lifted and worked as hard as you have.

Points That Work With Ciliao

The first partner sits higher up, on the lower back at waist level, two finger-widths out from the spine. In this tradition the two are worked together when a tired, aching back runs from the waist down into the base of the spine. A tennis ball against a wall reaches both.

The second lies lower in the buttock, level with the top of the cleft between the buttocks and about four finger-widths out to the side. It is used with this one when the ache spreads out from the base of the spine into the buttock.

The third sits in the middle of the crease at the back of the knee. It is one of the most used points for back pain in this tradition, and easy to reach from a chair. Work it after this one when the back is stiff and the legs feel heavy.

How to Find and Press Ciliao

Getting Into Position

This point is lower than most back points, and many people can reach it with their fingertips. Still, be honest about your shoulders and wrists. If reaching behind hurts, stand with your back to a wall, feet about a foot from it, knees soft, and use a tennis ball. Lying on your back on a carpeted floor with knees bent and the ball under the spot works too. A stick with a rounded end is a third way.

How to Find It

Reach behind and feel for the two small dimples low on your back, one on each side, about a hand's width apart. Under each lies a bony knob, the back of the hip bone. Not everyone has visible dimples, but the knobs are there to feel. From the lower edge of one knob, move about halfway in toward the centre line of the spine. Your fingertip should rest on flat bone, often over a slight hollow.

Place the ball or fingertips there and probe in small steps, a little up, down, in and out. Much of the area will feel like firm, flat bone under a thin layer of tissue. One spot will sting: a small, sharp, pinpoint tenderness. That spot is the point. If you feel the ridge of bone running down the centre of the sacrum, you are too far in; move out a little.

How to Press It

Stay on the stinging spot and rub in small circles about the size of a coin, roughly one each second. With a ball against the wall, bend and straighten your knees a little to make the circles. With fingertips, press straight in toward the front of the body and keep the tips still on the skin. Two balls tied in a sock work both sides at once, with the central ridge of the sacrum in the gap between them.

How Much Pressure

A sharp sting under the ball is right. When you lift off, it should fade within moments. If the pain stays after you lift off, spreads, or the area turns swollen, hot or red, stop and leave it for several days. Stop at once for any tingling or numbness in the buttock, between the legs or down a leg. If you are holding your breath or clenching your jaw, you are pressing too hard. Lean in less until you can breathe slowly through the sting.

How Long

One to three minutes on each side. Keep the first sessions to about a minute, because the tissue over the sacrum is thin and can feel bruised the next day. Add a little over the following days, up to three minutes. Work both sides, even if only one complains. Once or twice a day is plenty.

When to Do It

Morning suits a low back that is stiff on getting up. Late afternoon suits the deep ache that builds after sitting or driving. Before bed is a good time too, as part of winding down. Do not press in the middle of the night. If an aching back wakes you, getting up to lean on a wall will only wake you more. Keep it for the day and the evening.

What This Won't Do

It will not change wear in the joints between the sacrum and the hip bones, or a problem with a disc above. Pain at the base of the spine often comes from those places, or from the hip itself, and pressing on the surface does not reach them. It will not change pelvic organ problems either. What this point can do is ease the tight tissue over the sacrum and give you a calm daily routine. The things that change this kind of pain over months are plainer: breaks from sitting, a cushion that takes the weight off the base of the spine, walking, and gentle strengthening for the hips and buttocks.

Some pain in this area is urgent. Go to hospital the same day for numbness between the legs or around the back passage, or new trouble controlling your bladder or bowels. Get seen urgently if a leg turns weak. See a doctor promptly for pain after a fall onto the bottom, especially if your bones are thin, because the sacrum can crack with little force. See a doctor too for pain with fever, pain that is worse lying still at night, pain that worsens week on week, and any change in passing water.

Safety First

If you are pregnant, skip this one. The points over the sacrum carry a clear traditional caution in pregnancy. Do not press over skin that is broken, infected, badly bruised or rashy, or over a sore at the base of the spine. Leave the area alone after a recent fall onto the bottom, with a known fracture of the pelvis or sacrum, after recent back surgery, or with unexplained swelling or a lump. If you have thin bones, take blood thinners, bruise easily or have reduced feeling in your legs, use a softer ball, lean in less, keep sessions short, and ask your doctor first.

Stop at once if pain stays after you lift off, spreads, or brings tingling or numbness. 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 Ciliao (BL32) pressure point? Ciliao (BL32) lies on the sacrum, the flat triangle of bone at the base of the spine. Find the two dimples low on your back. The point is about halfway between each dimple and the centre line, a little lower, in a small hollow in the bone. In Vietnamese it is called Thứ Liêu.

How do I press a point on the back of my pelvis? Lean on a tennis ball against a wall, or lie on your back with the ball under the spot. Two balls tied in a sock sit on both sides at once. Many people can also reach this low area with their fingertips, because it is easier to get a hand to than the middle of the back. A stick with a rounded end works too.

What are the dimples on my lower back? They are small hollows in the skin over the two knobs at the back of the pelvis, where the hip bones meet the sacrum. Not everyone has visible dimples, but you can feel the bony knobs under them. They make a reliable starting point for this point.

Can Ciliao (BL32) help an ache at the base of the spine? In this tradition it is commonly used for pain in the low back and the sacrum, and for an ache that sinks into the pelvis. Pressing can ease tight tissue over the bone. It does not change wear in the joints between the sacrum and the hip bones, or a problem with a disc.

How long should I press Ciliao? One to three minutes on each side. Keep the first sessions to about a minute, then add a little as the days go on, up to three. Once or twice a day is enough. Work both sides.

Can I press Ciliao while pregnant? No. If you are pregnant, skip this one. The points over the sacrum carry a clear traditional caution in pregnancy. Ask your midwife or doctor about safe ways to ease back and pelvic pain.

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: BL32 · Ciliao · Second Crevice · Thứ Liêu.)