[Origin]

Yu refers to the acupoint, the hole in the back of the "lumbar acupoint" (sacral canal hiatus), hence the name.

[Location]

The midline of the sacrum is below the fourth sacral vertebra, suitable for the sacral canal hiatus. Lie prone, with the tail and sacrum slightly elevated, the lower limbs slightly internally rotated (the two big toes are close to each other), and a point is placed above the left and right sacral corners. In women, it generally forms an equilateral triangle with the two posterior superior iliac spines.

• Suwen‧Mouci Lun: "The solution to the waist joint";
• Zhenjiu Jiayi Jing: "Under the twenty-first vertebrae" "between";
• Donggong Anmo Mijue: "Stand down and relax your body, cross your hands to support your forehead, stretch your body behind you, and select the acupoints."

[Anatomy]

• Muscle: Sacrococcygeal ligament.
• Nerve: branches of the coccygeal nerve, and the sacral nerve is located above the sacral canal.
• Vessels: posterior branches of the middle sacral artery and vein, interspinous vein filaments.

[Manipulation]

Oblique insertion upwards 1 to 2 inches. Generally, it is not necessary to go deep into the sacral canal hiatus. If you need to penetrate the sacral canal hiatus, you can first feel the sacral angles on both sides of the midline about 4 to 5 centimeters upward from the tailbone, and then start from between the two sacral angles. Exploring the sacral canal hiatus upward, perform perpendicular insertion for 5 to 8 minutes or oblique insertion upward for 0.5 to 1 cun. If you need to go deep into the sacral canal, you can take the elbow and knee position. After inserting the needle to pierce the tough sacrococcygeal ligament (at this time, you will feel the resistance disappearing), the angle is 15° to 30° for adult men and 30° to 45° for women. Penetrate slowly. Because the lower end of the inferior cavity of the cobweb membrane ends at the plane of the second sacral vertebra, attention should be paid to the depth, which should not exceed one inch. moxa cone moxibustion 3 to 7 weeks, warm moxibustion with moxa sticks for 10 to 20 minutes.

[Efficacy]

It can benefit the waist, regulate blood circulation and stop diarrhea.

• Classical: strong pain in the lumbar spine, agonizing arthralgia in the waist and legs, muscle cramp in the feet, foot weakness, diarrhea, hemorrhage, hemorrhoids, epilepsy, stranguria, enuresis, menstrual irregularities, leukorrhea.
• Modern: Anorectal surgery with needle anesthesia, hemorrhoids, prolapse of lumbar intervertebral disc.

[Recipe]

• Not enough: Fengfu (GV16), Yaoshu (GV2).
• Lumback stiffness, immobility: Feishu (BL13), Yaoshu (GV2).
• Cold wind and cold paralysis: Yaoshu (GV2), Huantiao (GB30).