Atlas of Acupuncture

6.3 Extra Points: Back (EX-B)

Location

At the centre of the buttock, 3.5 cun lateral to the posterior mid-

line, on the level of the 4th sacral foramen.

How to find

Locate the lumbosacral joint, which often forms an easily palpa-

ble ‘kink’ between the L5 and the sacrum. Alternatively, locate

the Tuffier’s line (➞3.4.3) for reference. Then palpate the inferior

aspect of the sacrum for the sacral hiatus (➞3.4.4). Between

these two reference points, the four pairs of sacral foramina are

arranged on either side of the midline in a slight V-shaped form

and can be palpated as shallow depressions. Ex-B(tunzhong) is

located 3.5 cun lateral to the lowest depression (
4th foramen),

approximately at the centre of the buttock.

Located on the same level are ➞BL-34/BL-30/BL-54(over the

4th foramen/1.5/3 cun lateral to the midline).

Needling

Vertically 2–3 cun

Actions/Indications

● Opens the channel and luovessels locally

Special features

This is an unofficial extra point.

Buttock Centre TUNZHONG Ex-B

Midline3 cun

BL-54

Level of the

iliac crests

Sacral

foramina

tunzhong

3.5 cun

4

Spinous process L4

Spinous process L5

Sacral crest

BL-34

BL-33

BL-32

BL-31

Sacral hiatus

Fingers on the

1st to 4th sacral

foramina

Midline

BL-54

Sacral

foramina

Midline

Sacral

foramina

BL-30

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