scapulae
The clavicles are S-shaped bones that position the arms on the body. The clavicles lie horizontally across the front of the thorax chest just above the first rib. These bones are fairly fragile and are susceptible to fractures. For example, a fall with the arms outstretched causes the force to be transmitted to the clavicles, which can break if the force is excessive. The clavicle articulates with the sternum and the scapula. The scapulae are flat, triangular bones that are located at the back of the pectoral girdle. They support the muscles crossing the shoulder joint. A ridge, called the spine, runs across the back of the scapula and can easily be felt through the skin Figure 38.11 . The spine of the scapula is a good example of a bony protrusion that facilitates a broad area of attachment for muscles to bone. The Upper Limb The upper limb contains 30 bones in three regions: the arm shoulder to elbow , the forearm ulna and radius , and the wrist and hand Figure 38.12 .