Objective: For guiding clinical application of acupoints, the segmental distribution of sensory and motor neurons in the acupoints at different layers was investigated in this study. The segmental distribution of afferent neurons innervating intracutaneous, subcutaneous and muscular layers in three different depths of Zusanli (ST36) acupoint region were compared and investigated with HRP.

Results: The results showed that there exist slight differences in segmental distribution of sensory and motor nerves among the intracutaneous, subcutaneous and muscular 1ayers; If HRP was injected into the intracutaneous layer, the sensory neurons distributed mainly in the rostral portion. There were relatively more labeled cells located in fewer segments (L2-L5). Most of them were middle- and small type neurons; If HRP was injected into the muscular layer, the sensory neurons distributed mainly in the caudal portion. There were more labeled cells located in a broader range of segments (L3-S2); Most of them were large-type neurons; If HRP was injected into the subcutaneous layer, there were fewer sensory neurons labeled (L3-S1). These suggest that shallow puncture mainly treats local diseases and deep puncture is perhaps involved in treatment of visceral diseases.

Conclusion: Nerve distribution in muscular layer in the acupoint area may be more closely related with the internal organs.

By Li Ruiwu, Li Cuihong & Wang Zhimin