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Article
Directions of Torques Produced About the Ankle Joint by Cat Medial Gastrocnemius Motor Units
Motor Control
  • Alan J. Sokoloff
  • Timothy C. Cope, Wright State University - Main Campus
  • T. Richard Nichols
  • Arthur W. English
Document Type
Article
Publication Date
10-1-1997
Abstract
Differences in the directions of torque produced by motor units might be used by the nervous system to coordinate posture and movement. Here we report plantar flexion and abduction isometric torques exerted at the ankle by 158 motor units in the cat medial gastrocnemius (MG) muscle. In five cats, motor unit torque direction differed by an average of 10". Torque direction was weakly correlated with unit contraction time in 3 of 5 experiments, with tetanic force in 3 of 5 experiments, and with conduction velocity in 1 of 5 experiments. The direction of whole muscle torque, however, was constant at all levels of MG activation produced in sural and crossed extension reflexes. Thus, although there is a range in the direction of torque produced by motor units in the cat MG, we find no evidence for the ordering of motor units according to torque direction during MG activation.
Citation Information
Alan J. Sokoloff, Timothy C. Cope, T. Richard Nichols and Arthur W. English. "Directions of Torques Produced About the Ankle Joint by Cat Medial Gastrocnemius Motor Units" Motor Control Vol. 1 Iss. 4 (1997) p. 340 - 353 ISSN: 10871640
Available at: http://works.bepress.com/timothy_cope/92/