Application of the Action Current of Muscle to Anthropology

Abstract

Many anthropologists have been evolutionally Pursued the bodily transition of human race through the study of ancient human skeleton. Is it not possible to go by contraries? By starting from the study of existing human body, on the experimental stand-point, we might make clear the relation between the form and function and lay the foundation for explaining the ancient man. It is necessary to know in the first instance about the function of muscles in details.As the possible most accurate method we chose the action current of muscle. For all the electromyogram in this report, we induced the action current using the surface electrode, three stage-voltage and one stage power amplifyer and Yokokawa Co. type N-3 electromagnetic oscillograph.The author is obliged to explain much about his fundamental view of action current in the present report with little space for explanation about its application. As to the flexor and extensor groups respective action current of muscles can be purely separated by applying rather small electrode (diameter 0.9cm) to the skin (Fig. 3).PIPER stated that PIPER rhythm had nothing to do with the strength of the contraction of muscle. But, it appears when the load is laid on and the contraction is very strong. And this relation is not observed with all muscles ; for example, M. abductor hallucis, gastrocnemius and masseter do not show this rhythm at the strongest contraction (Fig. 7). As to the entity, of PIPER rhythm it is wrong to explain with the synchronous activity. It may be understood that PIPER rhythm appears as a three dimensional vector sum of motor units whose discharge frequency is about 50-.In muscle fatigue the frequency goes down to 20-. The author corroborated the existence of the two classified motor units, one discharge frequency at maximum 20-, the other 50-. The latter shows the so-called " phasic " part of movement and the former so-called "tonic" part. When the acivity of the lat ter discharge does not continue for a long time, the former works long. Accordingly the cause of muscle, fatigue is not to be attributed to the muscle fibre itself, but to motoneuron. The rhythm 20- comes out owing to the fact that with reduction of centripetal impulse, the facilitation at anterior horn cells of spinal cord diminishes.The problem of "flat feet" must be explained externally as the excessive extension of M. abd. hall. due to superfluous load. This muscle does not show show action current if large load is not applied to it. Therefore we find this muscle entirely acts reflexly. The one cause of flat feet may be considered the depression of function of M. abd. hall.. As the method to derive the internall cause is nit yet to be investigated, we should make the shoe sole adequate to the plantar arch.