The electromyographic study of the subclavius muscle (SM) was performed in 31 different movements, in 12 subjects (10 male and 2 female) aged from 17 to 28 years. The action potentials were obtained with an electromyograph Teca TE 4. Our findings suggest that the SM acts mainly on the stability of the sternoclavicular joint; with more or less intensity according to the degree of the clavicular interaction with the movements of the peripheral parts of the superior limb. The SM seems to act as a substitute for the ligaments of the sternoclavicular joint.