Reflex action on triceps surae fusimotor neurones evoked by stretch of contralateral hind limb muscles

Abstract

In most studies concerning reflex control of hind limb γ-moto-neurones so far published, only responses elicited from ipsilateral primary afferents have been thoroughly investigated. Crossed reflex actions on these cells from cutaneous afferents have also been studied by several authors. In comparison, there is only scanty information on reflex effects elicited from contralateral muscle afferents. In the few studies (see e.g. Grillner, 1969; Grillner et al. 1969) where such effects have been sought, only weak influences from contralateral muscle afferents on ipsilateral γ-motoneurones have been reported. In the present investigation it is shown that there exist potent excitatory reflex pathways from contralateral knee flexor (posterior biceps and semitendinosus) muscle receptors to ipsilateral ankle extensor (triceps) fusimotor neurones.