Objective The aim of this study was to examine the effects of deep branches of cervical plexus on trapezius muscle.Methods The evoked electromyography of 32 trapezius of 16 SD rats was examined in different time and results obtained were processed by statistical methods.Results After cutting the accessory nerves, stimulating the deep branches of cervical plexus evoked the myoelectricity, the myoelectricity results varied according to different time.Conclusion The deep branches of cervical plexus are another important motorial supply to trapezius muscles. After cutting the accessory nerves, if the branches were undamaged, the shoulder′s function would be greatly preserved.