Final answer:
The first seven ribs, known as true ribs, are directly attached to the sternum via their costal cartilages, while ribs 8-10, or false ribs, attach indirectly to the sternum via the cartilage of the next higher rib.
Step-by-step explanation:
Ribs 1-10 have distinct attachments. The first seven ribs, known as true ribs (vertebrosternal ribs), are directly attached to the sternum via their costal cartilages. This direct attachment allows for the front of the rib cage to be relatively rigid and helps protect vital organs such as the heart and lungs. Ribs 8-10 are referred to as false ribs (vertebrochondral ribs) because their costal cartilages do not attach directly to the sternum.
Instead, the rib cartilage of ribs 8, 9, and 10 connects to the cartilage of the next higher rib, creating an indirect attachment to the sternum. Specifically, the costal cartilage of rib 10 attaches to the costal cartilage of rib 9, rib 9 to rib 8, and rib 8 to rib 7.