Figure 7. Comparison of motor unit recruitment thresholds of the long multi-tendoned flexors and extensor of the human hand.

The mean motor unit recruitment thresholds during voluntary contractions of non-test fingers are plotted for all index, middle, ring and little finger units of the flexor digitorum superficialis (FDS; filled circles), flexor digitorum profundus (FDP; open circles) and extensor digitorum (ED; grey squares). Data for FDS and FDP are adapted from Butler et al. 2005.