The two bones in the back are called the scapulae. Some patients also commonly refer to them as the lute bones. There is one scapula on the left and one on the right. As the patient moves the shoulder joint, the patient can clearly feel the bones here move significantly in the back. The scapula is a triangular flat bone located in the upper part of the back, with its uppermost and lowermost edges located between the second and seventh ribs, respectively. The outermost part of the scapula has a depressed articular surface, which is called the articular glenoid. This, together with the humeral head, forms the main structure of the shoulder joint. Posterior to the scapula is a very distinctive high post, called the scapular post. The scapular post divides the posterior aspect of the scapula into the supraspinatus and infraspinatus fossae. Both the supraspinatus and infraspinatus fossae have a series of muscles attached to them and have associated blood vessels and nerves passing through them. On the anterior side of the scapula is a shallow fossa with a concave line, which faces the rib cage and therefore provides some protection to the posterior side of the human thorax.