A muscle spindle model and study the effects of static and dynamic γ stimulations on primary and secondary ending outputs

A linear lumped-parameter mechanical model of the muscle spindle is presented. It is shown that the model simulation exhibits the spindle behavior in most aspects of transient ramp-stretch performance. The requirements that such a model places on the mechanisms of fusimotor control are discussed. Then the efficacy of static γ and dynamic γ stimulation on primary ending output and secondary ending output is studied. The results of simulations show that primary ending of muscle spindle is affected either by static and dynamic stimulation and Secondary ending of muscle spindle is affected only by static fiber stimulation. The bias of primary ending output is increased by an increase in static γ stimulation. The Ramp of primary ending response is increased by an increase in dynamic γ stimulation. An increase in static γ stimulation in secondary ending of muscle spindle increases the dc level of secondary ending output so the bias of output is increased too.