In thoracic outlet syndrome, arterial type involves compromise of which structure?

• A. Subclavian artery
• B. Vertebral artery
• C. Brachial plexus
• D. Pulmonary artery

Answer: (A)

Arterial thoracic outlet syndrome involves compression of the subclavian artery as it passes through the thoracic outlet under the clavicle and first rib. This arterial structure is susceptible to pressure from surrounding bones and muscles in that tight space, and when it’s compressed, you can see reduced blood flow to the arm with symptoms like diminished pulses, coldness, fatigue with use, or ischemic claudication.

The other structures listed aren’t the arterial component of TOS. The vertebral artery isn’t typically affected by outlet compression in this context, and the brachial plexus is the neural component responsible for neurogenic TOS. The pulmonary artery is not involved in thoracic outlet mechanics.