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TThe Ionic-Mechano-Hydraulic (IMH) model of nerve conduction establishes that the action potential is a coupled ionic-hydraulic phase transition in which electrical events are causally secondary to a propagating pressure wave.The present paper identifies and formalises the elementary molecular mechanism underlying that model: a membrane-integrated protein actuator that alternates between an open V-shaped conformation and a closed U-shaped conformation, driven by ion capture and release.The actuator possesses two mechanical degrees of freedom --vertical displacement generating local hydraulic volume and horizontal compression transmitting tension to neighbouring membrane elements -- whose geometric coupling converts ion binding energy directly into a propagating pressure wave.The ion is recycled within the system by a membrane rotation step, satisfying the evolutionary parsimony constraint of the primitive cell operating in an anion-scarce environment.The surrounding polyelectrolyte gel acts simultaneously as an ion reservoir, a mechano-selective filter governed by the Hofmeister series, and an electrical mask that renders adsorbed ions invisible to external electrodes.Ca$^{2+}$ orchestrates the reset cycle: its dominant affinity for the anionic gel sites drives rapid gel re-compaction, forces the U$\rightarrow$V returntransition, and defines both the absolute and relative refractory periods.The metabolic cost is minimal, with one partial ATP hydrolysis per rotation cycle, with local consumption of O$_2$ and CO$_2$ producing providing intrinsic frequency self-regulation through pH feedback.The actuator fractally assembles: a ring of V$\rightarrow$U units constitutes an ancestral channel unit (level~1); a group of channels constitutes a Ranvier node (level~2); myelin-rigidified internodal segments constitute a hydraulic waveguide with velocity bonus (level~3).This hierarchy resolves, at molecular resolution, why unmyelinated C-fibres conduct at velocities that channel density alone cannot account for withinthe HH framework, why the refractory period has two kinetically distinct phases, and why electrical stimulation remains effective in the absence of a transmembrane ionic gradient.The V$\rightarrow$U actuator is proposed as the evolutionarily ancestral motor from which the Nav channel family was subsequently derived.