Microneurography from the posterior tibial nerve : a novel method of recording activity from the foot in freely standing humans

The posterior tibial nerve, located behind the medial malleolus of the ankle, supplies the intrinsic muscles of the foot and most of the skin of the sole. We describe a novel approach for recording from this nerve via a percutaneously inserted tungsten microelectrode, and provide examples of recordings from presumed muscle spindle endings recorded in freely-standing human subjects. The fact that the angular excursions of the ankle joint are small as the foot is loaded during the transition from the seated position to standing means that one can obtain stable recordings of neural traffic in unloaded, loaded and freely standing conditions. We conclude that this novel approach will allow studies that will increase our understanding of the roles of muscle and cutaneous afferents in the foot in the control of upright posture.