Background: Accumulating evidence from anatomical, physiologic, and neuroimaging research shows that Classical acupuncture points stimulate nerve trunks or their branches in the head, trunk, and extremities. The first part of this series revealed that phenomenon in the extremities. Principal meridian distributions mirror those of major peripheral nerves there and Classical acupuncture points are proximate to peripheral nerves there. These relationships were shown to be consistent with the linear neuroembryologic development of the extremities. The second part of this series revealed that, in the trunk, a neuroanatomical basis for the Principal meridians exists consistent with lateral folding in early fetal neuroembryologic development. Objective: The aim of this Part is to provide anatomical data that corroborates a neuroanatomical basis for the Principal meridians in the head and neck, which is consistent with the longitudinal and lateral folding that occurs in early fetal neuroembryologic development. Methods: Adobe Photoshop software was used to apply Classical acupuncture points and Principal meridians as layers superimposed on neuroanatomic images of the head and neck, allowing demonstration of their anatomical relationships. Results: The Principal meridian distributions in the head and region can be conceptualized as connecting branches of the cranial and/or cervical spinal nerves. Conclusions: Anatomical data support the conceptualization of acupuncture Principal meridians in the head and neck as connecting branches of the cranial and/or cervical spinal nerves and are consistent with neuroembryologic development. Overall, the acupuncture Principal meridians can be conceptualized to have a neuroanatomical substrate that is corroborated by developmental neuroembryology.
Keywords: acupuncture; mechanism; meridians; peripheral nerve.