Accessory nerve (spinal part)
This nerve is tested as follows.
Put your hands on the right and left shoulders of the
patient and ask him to elevate (shrug) his shoulders. In paralysis the movement
will be weak on one side (due to paralysis of the trapezius).
Ask the patient to turn his face to the opposite side
(against resistance offered by your hand). In paralysis the movement is weak on
the affected side (due to paralysis of the sternocleidomastoid muscle).