Shoulder

Thoracic outlet syndrome

Mechanism: Compression of the brachial plexus or the vessels in one of three narrow passages: between the scalene muscles, between clavicle and first rib, or beneath pectoralis minor. A cervical rib or a poor posture narrows that space further.
Recognition: Tingling and heaviness in the arm increasing with work above shoulder height or carrying a bag. Usually in the distribution of the lower plexus: ulnar side of forearm and hand.
Course: The provocation tests are positive in many healthy people, so no single test proves the picture. The diagnosis rests on the symptom pattern and on excluding cervical radiculopathy and a distal neuropathy.

Structures