Sternocleidomastoid muscle exhibits consistent muscle activation and elasticity tuning during 3-d isometric tasks

The complex anatomy of the neck creates uncertainty regarding how the central nervous system (CNS) activates individual muscles to stabilize the neck in 3-D. The CNS can tune both the activation and mechanics of muscle to preferred directions where the muscle maximally contributes to stability. In this experiment, we examined the stabilizing contributions of the sternocleidomastoid muscle (SCM) to 3-D isometric neck torque generation using electromyography (EMG) and ultrasound shear wave elastography (SWE). The preferred directions were consistent among individuals and EMG/SWE collections, and were not affected by the magnitude of volitional contraction.