It is a long, S-shaped bone. Four strong muscles are attached to the central part of the clavicle: the sternocleidomastoid muscle (m. sternocleidomastoideus), which is attached from the top closer to the sternal end; the greater pectoral muscle (m. pectoralis major), which is attached from the bottom closer the sternal end; the dorsal trapezius muscle (m. trapezius), which is attached closer to the shoulder end from above; and the deltoid muscle (m. deltoideus) from below the shoulder segment.