Figure 9: Patient with transient postoperative paralysis of the spinal accessory nerve. The illustrations on the left show the preoperative status with adequate and symmetrical innervation of the trapezius muscle during various movements of the arm and shoulder. In the illustrations on the right taken postoperatively one can easily discern the loss of muscle contour during the same movements. The inferior portion of the trapezius muscle is particularly affected, since the upper segments of the muscle is not solely innervated by the spinal accessory nerve.