The origin of the premotor potential recorded from the second lumbrical

When recording with a palm electrode, a premotor potential (PMP) precedes the compound muscle action potential evoked from the second lumbrical muscle following median nerve stimulation. The origin of the premotor potential has remained uncertain. The aim of this study was to determine whether the PMP-2L is a SNAP derived from antidromically activated digital sensory branches of the median nerve.We recorded three active electrodes were placed over the second lumbrical muscle, the third lumbrical muscle, the fourth lumbrical muscle by multi-channel recordings.PMPs are recorded only over the median digital sensory branches after stimulating the median nerve, while they are recorded only over the ulnar branch after stimulating the ulnar nerve.We conclude that the origin of the PMP is a SNAP arising from antidromically activated digital sensory branches.