Anatomically accurate model of EMG during index finger flexion and abduction derived from diffusion tensor imaging
Fig 7
Influence of physiological and anatomical factors on EMG amplitude when muscle anisotropy is neglected.
Data are as presented in Fig 6. (a) MUAP peak-to-peak amplitude as a function of distance from the electrode. The number of fibers in each motor unit is indicated by the diameter of the discs and the muscle state is indicated by color. The electrical profile of the muscle over the cross-section directly under the electrode array is shown in (b) and (c) for abduction and flexion, respectively. The reference voltage Vmax corresponds to the maximum voltage produced by these point sources across the two muscle states. Dashed lines mark levels of 5% decay in the voltage produced at the array. MUs for which the amplitude of their surface action potentials lay below the noise level have their territories indicated by dotted black lines. The remaining MUs have their surface AP levels indicated by the color of the center point and the territory line, according to the color scale given at the left side of the figure.