The most common sites for rib fractures are the fourth to tenth ribs, as they are more prone to fractures. The first to third ribs are relatively short and are protected by the scapula and clavicle. Additionally, the 11th and 12th ribs are quite mobile, making them less likely to fracture when subjected to external forces. Among the fourth to tenth ribs, the fourth to seventh ribs are the most susceptible to fractures, because their internal cartilage is relatively short, making these ribs the most likely to break when impacted.