Electrical Activity of the Intrafusal Muscle Fibres

Abstract

THE efferent regulation of sensory discharges in muscle proprioceptors is accomplished by activation of the intrafusal fibres through their motor nerve supply. Contraction of these fibres would produce stretch-deformation of the sensory nerve endings and thereby an increase in the frequency of afferent discharges. In the frog it is achieved mainly by activation of the large-diameter motor axons¹ while in the cat it is elicited only when the small nerve fibres are stimulated². Although the bulk of experimental evidence is quite convincing, it still remains largely indirect because direct observations on intrafusal fibre activity are few.