The electromyographic activity of the trapezius and deltoideus was analyzed using a 2-channel TECA TE4 electromyograph and needle electrodes in 16 male volunteers in the following movements of the shoulders elevation, lowering, protraction and retraction. The superior portion of the trapezius was active in the elevation and lowering of the shoulders. The middle and inferior portions were active in retraction. The deltoideus was practically inactive in all these movements.344243247