Final answer:
Between ribs 5-6-7-8-9-10 are costal cartilages, with ribs 8-10 being false ribs attached to the cartilage of the higher rib, not directly to the sternum.
Step-by-step explanation:
The human rib cage, also known as the thoracic cage, includes 12 pairs of ribs which are attached to the thoracic vertebrae at the back and to the sternum or to other ribs at the front. Between ribs numbered 5-6-7-8-9-10, we find the costal cartilages, which are extensions of the ribs that contribute to the elasticity and expansion capability of the rib cage, especially during breathing. The true ribs (1-7) are directly attached to the sternum, while ribs 8-10 are classified as false ribs because their costal cartilages attach to the cartilage of the higher rib rather than to the sternum directly. The floating ribs (11-12) do not attach to the sternum and have their costal cartilages terminating within the musculature of the lateral abdominal wall.