Asymmetry of the viscoelastic properties of the skin and muscle compartments of the left and right hands.

The aim of this research was to discriminate and categorize isolateral stress-strain characteristics contained within the musculocutaneous compartment (MCC) using the model of the first dorsal interosseous muscle (FDI) in vivo. In our approach, the musculocutaneous compartment of the dorsal interosseous muscle was progressively isokinetically compressed by a solid vertical bar with a 0.25 mm incremental step. During each step, the force and deflection were measured and recorded electronically. The subject maintained a constantly relaxed position. Twenty-two strongly right-handed young males returned three data acquisition sequences from each hand. From the sequences, the elastic modulus and the specific energy of deformation were determined for both the total musculocutaneous compartment structure and separately for the discrete cutaneous and muscular compartments. No unilateral pattern of dominance was interpreted from the analysis of the range of indices. There was a highly variable individual pattern of bilateral dominance with no specific indication or predictability represented by the data: only one subject illustrated a data profile confirming the classical approach to right-handed dominance. As the muscle was relaxed and the integument layers were under minimal cortical influence, we suggest that the classical theory of primary cortical influence in motor lateralization does not adequately explain our recorded patterns of mechanical response of the musculocutaneous compartment analyzed in this study.