Modeling surface action potentials of thenar muscles in human hand

Presents a methodology and simulations of surface single-muscle fiber action potentials of the thenar muscle in the human hand. Muscle fibers are allowed to follow their natural curvature, where the propagating point source (tripole) response method is used to obtain temporal action potentials recorded on palm surface stations. A realistic human hand is formulated by a sample surface method (SSM) based on contour characteristics, e.g. the creases on the fingers. The potential field due to a tripole on a fiber path is obtained using the finite element method (FEM). Three models (whole hand, palm/thumb and simplified palm/thumb) are simulated. The results show that the palm/thumb model is as good as the whole-hand model. However, the simplified palm/thumb model gives a different result, which suggests that the effect of local boundary geometry can be significant. Surface single-fiber action potentials recorded over the end-plate and muscle-tendon junction of the thenar eminence show the much more pronounced effects of muscle curvature when comparing the whole-hand model with the simplified palm/thumb model. With a realistically shaped hand model, we hope to simulate on-going EMG and compound muscle action potential (CMAP) studies to provide insight into the assessment of human hand muscle function.