The shoulder joint is formed by a combination of muscles and tendons designed to support the humerus (upper arm bone), shoulder blade (scapula), and collar bone. The human body has a great deal of range of motion that allows throwing motions and reaching the back; however, this great flexibility puts the shoulder at risk to overuse syndromes and injuries. Shoulder pain may start in the shoulder itself but it is not uncommon for it to come from the surrounding muscles, tendons, and ligaments.