Abundant nerve ending distribution in the acupoint: Anatomists fro m 10 medical colleges and institutes as Shanghai Medical University, etc observed that there existed abundant nerve endings within about 5 mm-diameter range of the acupoint area in majority of 2444 acupoints in the dead human body. In above 90% of the ob served acupoints, there were some nerve trunks or nerve branches to pass through . Results of the observations on 371 acupoints by scholars from France, Japan, Canada, the former Soviet Union, etc was very similar to those of Chinese scholar s. The relationship between acupoint locations and forms of nerve distribution are 1) acupoints are located in the superficial layer of the muscles where the nerves go out from the deep part. Most of them are acupoints on the head; 2) the distribution of majority of the acupoints along the meridian track is basically identical to the route running of nerve trunk; 3) some acupoints are located a t the converging sites of the cutaneous nerve branches on the bilateral sides of the midline of the body trunk; and 4) some acupoints distribute in the nerve branches.

Generation of needling sensations is closely associated with nerves: Location marking examination of the needling sensations conducted in volunteer cancer patients by scholars from Shanghai Institute of Acu-Moxibustion and Meridians, Anhui College of TCM and Japan showed that there were abundant nerves innervating the acupoint area, while in the sites where no any or very weak needling sensations appeared, there was few nerve distribution or the nerve tissue was injured.

Normal nerve function is the necessary prerequisite for generation of needling sensations. It was observed by medical workers of Guangzhou Military Region General Hospital that in lower-limb-paraplegia patients, puncturing Zusanli (ST 36) d id not generate no any needling sensations, had no any effect on the pain evoked potentials of the cerebral cortex and on the patient's pain threshold, while puncturing Hegu (LI 4) brought about a generation of clear needling sensations and an increase of the pain threshold.

After procaine-block or section of nerve innervation around the acupoint, the effect of acupuncture disappeared or was weakened greatly. Experimental studies of 13 units as Beijing Medical University, etc. demonstrated that acupuncture or moxibustion could raise pain threshold, enhance or inhibit the functional activities of the internal organs, strengthen the immune function, suppress the viscera l pulling reaction, muscular tension and the hypotension of hemorrhagic shock. W hen the acupoint was blocked by procaine or the nerves innervating the acupoint were cut off, the aforementioned effects of acupuncture stimulation vanished or were weakened considerably.

Direct stimulation of nerve trunk had a favorable effect on some diseases. Both clinical observations and animal experiments revealed that direct stimulation of nerve trunk could generate a good therapeutic effect on some diseases.

By Wang Pei  and  Wang Shaorong