Ribcage and upper body, computer artwork The spine, which consists of blocks of bone (vertebrae) separated by spongy intervertebral discs, runs down centre. The ribcage (centre) is made up of twelve pairs of curved bones that attach to the spine at the back and the sternum at the front. In front of the ribcage at top are the collar bones (clavicles). Behind the ribcage at top are the shoulder blades (scapulas). The clavicles and scapulas articulate with the upper arm bones (humerus) to form the shoulders.