Thoracic outlet syndrome

Thoracic outlet syndrome involves compression at the thoracic inlet, which is known clinically as the superior thoracic outlet, resulting from excess pressure placed on the neurovascular bundle passing between the anterior scalene and middle scalene muscles. It can affect one or more of the nerves that innervate the upper limb and/or blood vessels as they pass between the chest and upper extremity, specifically in the brachial plexus, the subclavian artery, and rarely, the subclavian vein.