SP 9 — Yīn Líng Quán (阴陵泉) — Yin Mound Spring

SP 9 (Spleen 9; Yin Ling Quan, “Yin Mound Spring”) is the He-Sea (Water) point of the Spleen meridian and the principal acupuncture point for resolving Dampness anywhere in the body. Located in the depression below the medial condyle of the tibia, just inferior to the lower end of the patella, it transforms damp accumulation, regulates urination, harmonises the Lower Jiao and treats medial knee pain. Used clinically for oedema, IBS-D, vaginal discharge, urinary tract infections, swollen knees and damp-pattern skin conditions.

On this page

1. Overview
2. Location
3. Actions
4. Indications
5. Needling
6. Clinical notes
7. Common point combinations
8. Treatment at my clinic
9. Frequently asked questions about SP 9

1. About SP 9 (Yin Ling Quan)

SP 9 — Yīn Líng Quán (阴陵泉) — is an acupuncture point on the Spleen meridian. Its English name, Yin Mound Spring, reflects the point’s classical character and location below the medial “mound” of the tibia. It is the He-Sea (Water) point of the Spleen channel and, in classical and modern TCM practice alike, the single most important point for resolving Dampness. It is used regularly in the treatment of oedema, IBS, urinary tract problems, medial knee pain and PCOS in acupuncture practice.

I am Dr (TCM) Attilio D’Alberto, a member of the British Acupuncture Council with over 25 years of clinical experience. I use SP 9 as part of individually tailored acupuncture prescriptions at my clinic in Wokingham, Berkshire.

2. SP 9 location

On the medial aspect of the leg, in the depression in the angle between the medial condyle of the tibia and the posterior border of the tibia. To find it, slide a finger up the inner edge of the shin bone (tibia) from the ankle — the finger will stop at a definite bony obstruction at the medial condyle, just below the knee. SP 9 sits in the small hollow on the underside of that bony angle. The point is typically tender to palpation in patients with Damp patterns.

3. Actions

1. Resolves Dampness and benefits the Lower Jiao — the primary action
2. Benefits the Spleen and harmonises the Middle Jiao
3. Promotes urination and opens the water passages
4. Clears Damp-Heat from the Lower Jiao
5. Treats medial knee pain (local action)

4. Indications

1. Oedema and fluid retention — primary point for draining Dampness from the body
2. Urinary difficulty, urinary tract infections and urinary incontinence
3. Abdominal distension, diarrhoea (IBS-D) and digestive Damp
4. Medial knee pain from Damp accumulation — the most important local point for knee pain
5. Vaginal discharge and leucorrhoea from Damp in the Lower Jiao
6. PCOS from Phlegm-Damp obstruction
7. Damp-pattern skin conditions — weeping eczema, fungal infections, athlete’s foot
8. Heavy, swollen sensation in the limbs

5. Needling

Perpendicular insertion 1.0–2.0 cun. Strong De Qi sensation is often achieved, sometimes radiating into the medial knee or down the medial calf.

Important: Acupuncture should only be performed by a fully qualified practitioner. Never attempt self-needling. All needles I use are sterile, single-use and disposed of immediately after treatment in a clinical sharps container.

6. Clinical notes

SP 9 is the He-Sea and Water point of the Spleen meridian. In the Five-Element system, the He-Sea point of a Yin meridian governs “rebellious Qi and diarrhoea”, and the Water point on the Earth (Spleen) channel is unusually effective at draining water and damp from the body. These two classical attributes converge in SP 9’s reputation as the single most important point for resolving Dampness.

In modern clinical practice, SP 9 is reached for whenever a Damp pattern is identified: a swollen, scalloped tongue with a thick coating; loose, sticky or sluggish stools; heaviness in the limbs; sticky vaginal discharge; oedema around the ankles or knees; or the characteristic morning puffiness of Spleen Qi deficiency with Damp. In gynaecological practice it is essential for PCOS treatment where Phlegm-Damp obstruction prevents ovulation. For knee pain, SP 9 addresses the Damp accumulation that frequently contributes to medial knee pain, oedema around the joint and post-surgical knee swelling.

The point is typically palpably tender in patients with significant Damp; the tenderness diminishes over a course of treatment as the underlying pattern resolves, giving the practitioner a reliable index of clinical progress.

7. Common point combinations

1. SP 9 + ST 40 (Fenglong) — the classical combination to resolve Phlegm-Damp throughout the body, used for everything from PCOS to chronic productive cough to weight gain with sluggish digestion.
2. SP 9 + SP 6 (Sanyinjiao) — broadens the action to all three Yin meridians of the leg, supporting Liver and Kidney alongside Spleen. Used for menstrual irregularities with Damp, urinary problems and lower body fluid retention.
3. SP 9 + CV 9 (Shuifen) — the “Water Separation” combination for oedema, particularly above the waist or in the face.
4. SP 9 + BL 22 (Sanjiaoshu) — back-shu of the Triple Burner with SP 9 for systemic fluid metabolism problems and chronic oedema.
5. SP 9 + LI 11 (Quchi) — clears Damp-Heat from the body, particularly for skin conditions and urinary tract infections.
6. SP 9 + ST 36 (Zusanli) — tonifies Spleen Qi while resolving Damp, the standard pair for digestive disorders with weak digestion and Damp accumulation.

8. Treatment at my clinic

I use SP 9 as part of tailored acupuncture prescriptions for conditions including PCOS, knee pain, urinary tract infections, digestive disorders, irritable bowel syndrome, and damp-pattern skin conditions. Each treatment is individually designed following a full TCM assessment.

I see patients in person at my clinic in Wokingham, Berkshire. Visit the prices page for consultation fees. Return to the acupuncture points directory or the acupuncture main page.

9. Frequently asked questions about SP 9

What are the acupuncture points SP9 used for?

The acupuncture points SP9 (Yin Ling Quan) are used primarily to resolve Dampness in the body. The most common clinical uses are oedema and fluid retention, IBS with loose stools, urinary tract infections, urinary incontinence, medial knee pain, vaginal discharge and PCOS from Phlegm-Damp obstruction. Acupuncture points SP9 are the single most important point in Chinese medicine for clearing Damp.

Where do you press acupressure points SP9?

To find the acupressure points SP9: slide a finger up the inner edge of the shin bone from the ankle. The finger will stop at a bony obstruction just below the inner knee — the medial condyle of the tibia. SP 9 sits in the small hollow on the underside of that bony angle. Apply firm pressure with your thumb for 1–3 minutes. The point is often noticeably tender in people with Damp patterns. Always press acupressure points SP9 on both legs for a balanced effect.

Can SP 9 help with knee pain?

Yes. SP 9 is the most important local point for medial knee pain, particularly when there is associated swelling, fluid accumulation or a sensation of heaviness in the joint. It is regularly used after knee surgery to reduce post-operative oedema, and in osteoarthritis with effusion. For lateral knee pain, GB 34 is the corresponding local point; for posterior knee pain, BL 40.

Can SP 9 help with oedema and fluid retention?

Yes — this is SP 9’s primary classical action. Acupuncture at SP 9 stimulates urinary output, drains accumulated fluid from the tissues and addresses the underlying Spleen weakness that allows Damp to accumulate. It is the first point used for ankle oedema, lower-leg swelling and the morning puffiness of mild fluid retention. For more systemic fluid accumulation it is combined with ST 40 (Fenglong) and CV 9 (Shuifen).

Can SP 9 help with PCOS?

SP 9 is one of the core points used in acupuncture treatment for PCOS, particularly the common Phlegm-Damp pattern that presents with weight gain, irregular or absent ovulation, oily skin and a heavy, sluggish quality. It is combined with ST 40 (Fenglong) to resolve Phlegm-Damp and with SP 6 (Sanyinjiao) to regulate the menstrual cycle. PCOS treatment typically uses SP 9 over a course of 8–12 weeks alongside dietary changes.

What does SP 9 mean in Chinese?

SP 9 is called Yīn Líng Quán (阴陵泉) in Chinese, which translates as “Yin Mound Spring”. Yin refers to the medial (Yin) aspect of the leg, Ling (“mound”) refers to the prominent medial condyle of the tibia under which the point sits, and Quan (“spring”) reflects the point’s ability to release accumulated water from the body. The name encodes both the anatomical location and the clinical function.

Is SP 9 safe during pregnancy?

Yes, SP 9 is generally considered safe during pregnancy and is sometimes used to manage pregnancy-related oedema in the second and third trimesters. Unlike SP 6 (Sanyinjiao), which is strictly contraindicated, SP 9 has no documented uterotonic effect and is regularly used clinically for ankle and lower-leg swelling in pregnant patients under qualified care.