Sensation is intact in the upper extremities. Muscle stretch reflexes are normal and symmetric. Cervical range of motion is normal and pain-free. Spurling maneuver is negative. There is no tenderness over the supraspinatus insertion or bicipital groove.
Impingement sign is negative.
Active abduction of the right shoulder is full, but scapulohumeral rhythm is grossly abnormal. At this point, review your differential diagnosis and revise as appropriate. The presence of unilateral scapular winging connotes a neurogenic process and is highly suggestive of a long thoracic or spinal accessory neuropathy. Additional provocative maneuvers should be performed to better characterize the winging. Cervical radiculopathy and upper trunk plexopathy are less likely, given the lack of other neurologic abnormalities.