Forelimb responses to cutaneous nerve stimulation during locomotion in intact cats.

The reflex responses of forelimb muscles to electrical stimulation of the cutaneous superficial radial nerve were recorded during treadmill locomotion in chronically implanted cats. In brachialis and cleidobrachialis (muscles which are active mainly during the swing phase) the responses were maximal during the swing phase and minimal or absent during the stance phase. In the long head of triceps which is active mainly during the stance phase, responses were also minimal during stance and maximal during swing. It is concluded that, for some muscles, the period of maximal reflex responsiveness can be out of phase with the period of the step cycle during which they are normally active.