Trapezius muscle works as the opposite side rotation and same side flexion of the neck, so, accessory nerve injury, nitration injury should be with the same side rotation and shoulder depression. Is that right? But Magee suggests, it is with the opposite side neck rotation and shoulder depression. Please, correct me.

The unique clinical presentation that accompanies damage to the accessory nerve arises from the fact that the accessory nerve innervates both the Stenocleidomastoid (SCM) and Trapezius muscles.

The SCM controls opposite side neck rotation while weakness of the trapezius muscle can produce a drooping shoulder, winged scapula and a weakness of forward elevation of the ipsilateral shoulder. Therefore, Magee’s suggestion is right.