Fig. 3. Action potentials (A,B) and twitch tension (C) in response to a single motor nerve stimulation. The distance between the recording electrode and the point at which motor nerve entered into the SBM was 0 mm in A and 1.4 mm in B. In this and Fig. 4, broken vertical lines and arrows in A and B indicate the interval between the onset of stimulating current pulse and the onset of action potential.