The correct answer is 2. Thoracic outlet syndrome (TOS) complex refers to a series of neurovascular compression syndromes in the shoulder region, in particular, a compression vasculopathy of the subclavian vessels but more commonly involving the lower trunk or medial cord of the brachial plexus.

 Ulnar nerve entrapment, but these patients never have a sensory loss in the proximal or middle portions of the forearm. In addition, these patients should have no atrophy of the intrinsic muscles innervated by the median nerve in the thenar eminence.

Although carpal tunnel syndrome may cause thenar atrophy, the sensory loss, if present, manifests in the first two digits.

Pronator teres syndrome shares many of the same symptoms as TOS, but its symptoms are primarily at the elbow, with radiation into the radial aspect of the hand and numbness that extends into the median nerve distribution. In TOS, the pain generally arises in the shoulder and the proximal area of the arm with radiation into the ulnar aspect of the hand and numbness experienced in the fifth digit and along the ulnar aspect of the forearm.