What describes paradoxical motion of the chest?

• A. Part of the chest moves inward during inspiration while the rest of the rib cage moves outward during expiration
• B. The entire chest expands uniformly during inspiration
• C. The chest wall remains still during respiration
• D. Breathing causes only abdominal movement

Answer: (A)

Paradoxical chest motion happens when a portion of the chest wall moves opposite to the rest of the chest during breathing. In a flail segment, that part moves inward during inspiration as the chest normally expands, and then moves outward during expiration as the chest relaxes. This opposite movement reduces effective ventilation and is a sign of significant chest trauma requiring rapid assessment and airway/ventilation support. The other descriptions describe normal chest expansion, no movement, or solely abdominal breathing, none of which capture the opposite-direction motion that defines paradoxical movement.