The Lateral Flexion Test for the 1st Rib is used to assess which condition?

• A. Thoracic Outlet Syndrome
• B. Rotator Cuff Tear
• C. Carpal Tunnel Syndrome
• D. Elbow Tendinopathy

Answer: (A)

The test focuses on how the first rib moves and contributes to space at the thoracic outlet. In thoracic outlet syndrome, neurovascular structures—the brachial plexus and the subclavian vessels—can be compressed where the rib, clavicle, and scalene muscles meet. Lateral flexion of the neck changes the tension and position of the scalenes and the first rib. If there’s a dysfunction or abnormal mobility of the first rib, this maneuver can reproduce symptoms or reveal an abnormal rib movement during palpation, indicating compression at the upper outlet. That’s why this test is used to assess thoracic outlet syndrome, specifically related to first-rib mechanics.

Rotator cuff tear, carpal tunnel syndrome, and elbow tendinopathy involve structures farther down the kinetic chain in the shoulder girdle, wrist/hand, or elbow, and do not rely on first-rib motion or thoracic outlet mechanics.