Paradoxical movement refers to

• A. Chest segment moves opposite normal during breathing
• B. Lung expands normally during inspiration
• C. Breathing returns to baseline quickly
• D. No chest movement during breathing

Answer: (A)

Paradoxical movement occurs when a portion of the chest wall becomes unstable and moves in the opposite direction to the rest of the chest during breathing. In a flail chest, several consecutive ribs are fractured in two places, creating a free-floating segment. During inspiration, the negative pressure inside the chest pulls that segment inward, while the surrounding chest expands outward. During expiration, the segment moves outward as the chest compresses, again opposite to the normal motion. This reversed, or paradoxical, movement is the defining sign. The other statements describe normal lung expansion, a quick return to baseline, or no chest movement, none of which capture this reversed chest-wall motion.