Final answer:
When the external intercostal muscles contract, the rib cage is compressed. In individuals with flail ribs, the affected ribs c) move paradoxically. This can cause severe discomfort and difficulty breathing.
Step-by-step explanation:
When the external intercostal muscles contract, the rib cage is compressed. This is because the external intercostal muscles connect adjacent ribs and when they contract, they pull the ribs closer together, decreasing the space between them. This compression of the rib cage has important implications for individuals with flail ribs. Flail ribs occur when multiple adjacent ribs are fractured in multiple places, making the affected section of the rib cage unstable. When the external intercostal muscles contract in individuals with flail ribs, the affected ribs move paradoxically, meaning that they move in the opposite direction of normal rib cage movement during breathing. This paradoxical movement of the affected flail ribs can cause severe discomfort and difficulty breathing for individuals with this condition. It is a serious injury that requires medical attention for proper management and healing.