The scientific name for a shoulder blade is "scapula," according to ShoulderDoc. It is one of three bones that form the shoulder. The other two bones are the humerus (the upper arm bone) and the clavicle (collar bone).
ShoulderDoc states that the scapula is a large, flat bone in the shape of a triangle, and it forms the anterior part of the shoulder girdle. It glides along the back of the chest, allowing the arm a great range of motion.
How Stuff Works explains that flexible muscles attach the shoulder blade to the neck and upper back, providing the arm with a great deal of mobility. If these muscles become tired, stretched or tight, pain and loss of shoulder mobility can result.