Final answer:
Rib 11 and 12 are known as floating ribs and do not attach to the sternum or another rib. They are short ribs that terminate within the musculature of the lateral abdominal wall.
Step-by-step explanation:
The last two ribs, ribs 11 and 12, are called floating ribs.
They are short ribs that do not attach to the sternum or to another rib.
Unlike the other ribs, which have a costal cartilage that attaches them to the sternum, the floating ribs do not have a costal cartilage and terminate within the musculature of the lateral abdominal wall.