Estimation of the number and size of human flexor digiti minimi muscle motor units using histological methods.

Motor unit (MU) number and size estimates were obtained from the human flexor digiti minimi muscle using histological methods. Ten adult fresh cadavers (33-74 years old) were used. The number of MUs was 130 +/- 15 and the MU size was 108 +/- 10. These values are similar to those reported for other hypothenar muscles, using the same criteria. The results here described are in best agreement with those reported by the incremental and automated incremental methods.