Asymmetry in contralateral muscle excitation in proximal vs. distal muscles in upper extremities

These findings highlight neurophysiological distinctions of the dominant side, especially in distal muscles where refined neural circuits support greater CME. In contrast, the absence of asymmetry in proximal muscles is consistent with their stronger bilateral communication, facilitated by denser interhemispheric and spinal commissural pathways. Overall, the results indicate that CME asymmetries are shaped by both cortical specialization and structural differences in neural connectivity, offering new insight into how dominance and proximal-distal distinctions interact in motor control.