Tendon excursion and moment arm of index finger muscles

Tendon excursions during rotation of individual index finger were recorded continuously throughout the joints' ranges of motion. Both intrinsic and extrinsic muscles were studied during flexion--extension and abduction--adduction functions. Excursions and joint-displacement relationships were observed to not always be linear. Moment arms of tendons with respect to joint centers were further derived from excursion data. The significance of this information to tendon transfer techniques is discussed. These data are also important for theoretical modeling in muscle force determination.