[Objective]More accurate data of the relationship between the composition and distribution of the pelvic plexus and hachiryoketsu is discussed to get an effective acupuncture method.
[Methods]Detailed dissections were performed under a stereomicroscope in five cadavers belonging to the Unit of Clinical Anatomy, Graduate School, Tokyo Medical and Dental University.
[Results]1. The pelvic plexus is composed of the sympathetic hypogastric nerve and sacral splanchnic nerve, and the parasympathetic pelvic splanchnic nerve.
(1) The hypogastric nerve arises from the superior hypogastric plexus contributing constantly to the second and third lumbar splanchnic nerves, and enters the postero-superior horn of the pelvic plexus. The sacral splanchnic nerves arise from the third and fourth lumbar gangalia and enter the postero-inferior horn of the pelvic plexus.
(2) The pelvic splanchnic nerves mainly arise from the most ventral layer of the ventral primary of the third and fourth sacral nerves, and enter the postero-inferior horn of the pelvic plexus. These nerves tend to compose the common trunk with the pudendal nerve and the nerve to the levator ani.
2. The visceral branches of the pelvic plexus do not originate and distribute equally, but tend to divide into I-IV groups. Especially, group III is considered important clinically as these nerves are related to sexual and voiding functions.
[Conclusion] 1. BL33(Zhongliao, Churyo) and BL34 (Xialiao, Geryo) are suggested to have an effect on the function of the intrapelvic organs as these acupuncture points can stimulate the pelvic splanchnic nerves directly rather than BL31 (Shangliao, Joryo) and BL32 (Ciliao, Jiryo).
2. The point of the needle into the hachiryoketsu reaches the side of the rectum, so treating with a needle to the median direction should be avoided or paid attention to.