Arterial thoracic outlet syndrome involves compromise of which structure?

• A. Brachial plexus
• B. Internal jugular vein
• C. Axillary nerve
• D. Subclavian artery

Answer: (D)

Arterial thoracic outlet syndrome is about compression of the subclavian artery as it passes through the thoracic outlet, where the space between the clavicle and first rib (and nearby scalene muscles) can narrow. When this artery is compressed, the result is ischemic symptoms in the upper limb, such as diminished pulses, arm fatigue, or cool, pale hands. The other structures listed are more aligned with other forms of thoracic outlet syndrome or are less relevant to the arterial variant: the brachial plexus is the nerve bundle involved in neurogenic TOS; the internal jugular vein is not the vessel typically compressed in this syndrome; and the axillary nerve isn’t the primary structure affected in thoracic outlet compression.