Of the 12 ribs, how many attach directly to the sternum?

The correct answer is based on the anatomy of the ribcage. The human ribcage consists of 12 pairs of ribs. Among these, the first seven pairs are classified as "true ribs," which means they have direct attachments to the sternum through individual costal cartilages. Each of these seven pairs connects directly to the sternum, providing structural support and protecting vital organs such as the heart and lungs.

The remaining ribs have different classifications: the 8th to 10th pairs are known as "false ribs," as they do not attach directly to the sternum. Instead, they connect to the 7th rib's costal cartilage. The last two pairs, known as "floating ribs," do not attach to the sternum or to any costal cartilage, which allows for greater flexibility in the ribcage.

Understanding this anatomy is crucial for anyone in the chiropractic field, as it relates not only to structural integrity but also to the mechanisms of the respiratory system and the potential implications for spinal and musculoskeletal health.