Adson's test is performed by palpating the radial pulse and moving the arm into which position with the head turned toward the involved side and a deep breath taken?

• A. Abduction, extension, external rotation; head toward involved side; deep breath
• B. Adduction, internal rotation; head away
• C. Flexion, extension; head neutral
• D. Abduction, flexion; head toward involved side

Answer: (A)

Adson's test checks for thoracic outlet syndrome by provoking compression of the subclavian artery as the scalene interval is stressed. Positioning the arm in abduction with extension and external rotation places the shoulder in a way that narrows the space between the clavicle, first rib, and scalene muscles. Turning the head toward the involved side and taking a deep breath further tightens the scalene muscles and lowers the first rib during inspiration, increasing the likelihood of vascular compression. A diminished or lost radial pulse on that side indicates the test is positive, pointing to arterial compromise in the thoracic outlet region. Other arm/neck positions don’t load the same outflow space or rely on inspiration to provoke the compression, so they’re less consistent with this particular provocative maneuver.