Fusimotor stimulation and the dynamic sensitivity of the secondary ending of the muscle spindle

The response of secondary endings of de‐efferented muscle spindles in the soleus muscle of the anaesthetized cat was recorded during stretching of the muscle at velocities of 5‐30 mm/sec. Stimulation of single fusimotor fibres, most and probably all of which were static fusimotor fibres, produced no appreciable change in the normally small dynamic sensitivity of these endings.