The Central Bone-Hole of the sacrum. Zhongliao (BL-33) sits in the third sacral foramen and works quietly but powerfully on the lower Jiao — relieving pain, regulating the bladder and uterus, and restoring flow where things have become stuck or blocked.
Name & story
The name 中髎 Zhongliao means "Central Bone-Hole" — and it earns its name simply by where it lives. The sacrum has four pairs of foramina, those small natural openings in the bone, and BL-33 occupies the third one, sitting right between its neighbours: Upper Bone-Hole (BL-31), Second Bone-Hole (BL-32), and Lower Bone-Hole (BL-34). It is the middle of the series, the centre of the row. In classical texts it is sometimes called just that — the point "in the middle opening, in the depression on either side of the spine." There is a quiet elegance to this naming: it describes exactly what you will find when you look for it.
Point family & character
BL-33 belongs to the Bladder Meridian (BL). According to the Great Compendium of Acupuncture and Moxibustion, it is a meeting point of the Bladder, Liver and Gallbladder channels — meaning that three channels converge here, which partly explains its wide reach over the lower Jiao. It is one of the eight "Bone-Hole" points (BL-31 through BL-34), a group of four pairs that all sit in the sacral foramina and all share a strong affinity for the pelvic organs.
Five-element dynamics
The Bladder Meridian (BL) belongs to the Water element, and BL-33 sits in the very heart of the sacrum — the bony cradle of the lower Jiao. In Chinese medicine, the lower Jiao is the domain of the Kidneys, Bladder, uterus and intestines. When Qi Stagnation, Cold or Dampness settles in this region — whether from lifestyle, overwork or constitutional weakness — things stop flowing: pain appears, urination becomes difficult, menstruation falters. BL-33, right at the centre of the sacral openings, helps open those pathways again, regulating and moving what has become blocked.
Location
BL-33 lies in the third sacral foramen. To find it, locate the sacral crest (the ridge of bumps running down the centre of the sacrum) and feel for the third bony prominence from the top. The point sits in the depression just to the side of that level, in the natural opening of the bone. It is found below BL-32 and above BL-34, midway along the row of sacral foramina.
Anatomy & fascia
The point is located over the posterior surface of the sacrum, directly over the third posterior sacral foramen.
Needling
The needle is inserted perpendicularly, directed into the sacral foramen. The classic description places it "in the depression on either side of the spine" — the foramen itself guides the needle in.
Moxa, cupping & Tui Na
Moxa is well suited to this point, particularly when Cold or Yang Deficiency underlies the pelvic complaint — for example, cold-type menstrual pain or urinary difficulty with a sense of cold in the lower back. Gentle local massage over the sacrum is a useful home-care complement.
Functions
Regulates the lower Jiao and benefits the Bladder and uterus. Moves Qi Stagnation and relieves pain in the lumbar and sacral region. Resolves Dampness and regulates urination. Supports menstrual regularity and addresses disorders of the genitals and anus.
Indications
Lumbar and sacral pain; stiffness and pain in the lower back. Urinary difficulty, dysuria, retention or frequent urination. Menstrual irregularities, painful menstruation. Disorders of the genitals and anus. Conditions of the lower Jiao involving the intestines, Bladder and uterus.
Point combinations
As one of the Bone-Hole group, BL-33 is often combined with its neighbours — BL-31, BL-32 and BL-34 — to strengthen the overall effect on the pelvic organs. For menstrual disorders it may be paired with local points addressing the uterus and lower abdomen. For urinary complaints it works well alongside other Bladder channel points that regulate the lower Jiao.
Clinical spotlight
What makes BL-33 particularly interesting is its classical status as a meeting point of three channels — Bladder, Liver and Gallbladder — noted in the Great Compendium of Acupuncture and Moxibustion. This triple convergence at a single sacral foramen gives the point a broader reach than you might expect from its quiet, anatomical name. While all four Bone-Hole points (BL-31 through BL-34) share the same general territory, BL-33's position at the centre of the group, combined with this three-channel meeting, makes it a natural choice when the lower Jiao needs both regulation and movement.
The golden tip
For lower back and sacral ache, gentle circular massage over the centre of the sacrum — the flat triangular bone at the base of the spine — can help ease tension and encourage Qi flow in the area. Warmth is especially helpful: a warm pack or hot water bottle placed over the sacrum is a simple and effective complement, particularly when the pain feels worse in cold weather or is linked to menstrual discomfort.
For education only — not medical advice. Consult a qualified practitioner.