[Research progress of Shenshu (BL 23)].

In order to accurately understand the location of Shenshu (BL 23) and to improve the efficacy of acupuncture, a discussion is performed in this paper from aspects of acupoint function, anatomical structure, experiment research, clinical application, etc., hoping to provide benefit for future animal experiments and clinical selection of acupoint. The characteristics of rat spine is different from that of human, and the reliability and authenticity of acupoint location would be compromised if the anatomical characteristics of human was inflexibly applied on animals. "Shenshu" (BL 23) belongs to the bladder meridian of foot taiyang , and is located 1.5 cun lateral to the lower border of the spinous process of the second lumbar vertebra. It is close to kidney, therefore deep insertion or repeated lifting and thrusting of needle would damage kidney and causes acupuncture accident. Therefore, to locate "Shenshu" (BL 23) in rat, the 6th lumbar vertebra is located firstly based on tuber coxae of rat, and then 11th thoracic vertebra is located by upward 4 vertebral bodies or locate 9th to 11th thoracic vertebra which are tight, and finally 2nd lumbar vertebra is located by downward 4 vertebral bodies, and "Shenshu" (BL 23) is 5 mm lateral to it. During clinical treatment, the technique should be gentle; oblique and outward insertion of needle is not allowed; the maximum depth of needle insertion is 1.6 cun (approximately 4.30 cm); the vertical or oblique insertion with needle 45° towards spine is appropriate; the depth of 0.8 to 1.2 cun (2.00 to 3.10 cm) is suitable. In cases of too thin or fat patients, the depth of needle insertion should be adjusted for safety.