Reciprocal inhibition, synergies, and movements.

This paper presents a conceptual scheme relating discrete motor entities, such as muscles, joints, synergies and reflexes, to a continuous space of movements. Synergies are first derived as combinations of muscles, with reference to Ia reciprocal inhibition. Derived synergies may be modified into bases (in the linear space sense) for movements. The empirical example discussed is human postural synergies. The methods presented provide a relatively simple means for describing the control of bending and twisting movements about a joint by multiple muscles, joined by modifiable spinal interconnections.