The fascial-interstitial system and the sanjiao-mocou system: an analogy-based hypothesis for the anatomical basis of meridian pathways

Background The anatomical basis of meridian pathways remains a central challenge in modernizing Traditional Chinese Medicine (TCM). Concurrently, modern science has redefined the integrated fascial-interstitial system as a pervasive, fluid-filled cavitary organ system involved in signaling and transport. This parallel invites novel theoretical integration. Objective This review proposes a translational hypothesis positing that the classical TCM concept of the “Sanjiao-Mocou” system is analogous to the modern fascial-interstitial system, together constituting the anatomical and functional substrate of meridians. Methods We conducted a systematic comparative analysis of classical TCM texts describing the Sanjiao (Triple Energizer) and Mocou (interstitial spaces) and contemporary literature on the structure and function of the fascial-interstitial system. This theoretical integration focuses on their shared attributes: being ubiquitous, fluid-transporting, cavity-containing connective tissue systems that facilitate systemic communication and homeostasis. Findings The hypothesis elucidates how the Sanjiao-Mocou system, long understood as the “passageway for Yuan-Primordial Qi and body fluids,” aligns closely with the fascial-interstitial system’s role in interstitial fluid transport, mechanotransduction, and immune surveillance. This analogy provides a coherent, testable model where meridians may be conceptualized as specialized functional channels within this pervasive cavitary organ. Conclusion The proposed analogy bridges a foundational TCM theory with contemporary biomedical science. It offers a potential anatomical framework for understanding meridians and opens new avenues for interdisciplinary research in biomechanics, fluid dynamics, and integrative physiology, potentially advancing the understanding of both TCM and fascial science.