Processing of myoelectric signals for estimating the location of innervation zones in the skeletal muscles.
An electrical activity associated with the excitement of muscle fibers arises from the myoneural junctions located at the middle length of the fibers and propagates to the both ends. This propagation can be detected with a multi-electrode array placed on the skin surface. Therefore, the position of the myoneural junctions, or of the innervation zones as a collection of myoneural junctions, can be estimated from the source of the propagation. The authors propose a method for determining the position of the propagation sources automatically with a computer. The method was based on the line-source model of muscle fibers. The positions of the propagation sources were treated as parameters in the model. When some values are assigned to the parameters, the surface potentials are calculated from the currents assumed to propagate on the muscle fibers. The computer searched for the optimal parameters which gave the best fit between the calculated and the measured potentials on the skin surface. Using this method some separate sources of propagation were detected at the middle length of the biceps brachii. The activity of the individual innervation zones was quantitatively described by the average amplitude of the potentials arising from the corresponding sources. This description clarified the changes in the activity of innervation zones when the contraction forces were varied.
Masuda
T
T
Industrial Products Research Institute, Tsukuba Science City, Ibaraki, Japan.
Sadoyama
T
T
D000200:Action Potentials / Q000502:physiology; D004566:Electrodes; D004576:Electromyography; D006801:Humans; D009119:Muscle Contraction / Q000502:physiology; D009132:Muscles / Q000294:innervation*; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted