shoulder

shoulder A structure that is made up of two main bones: the scapula (shoulder blade) and the humerus (the long bone of the upper arm). The end of the scapula, called the glenoid, is a socket into which the head of the humerus fits, forming a flexible ball-and-socket joint. The scapula is an unusually shaped bone. It extends up and around the shoulder joint at the rear to create a roof called the acromion, and it extends around the shoulder joint at the front to constitute the coracoid process. See also shoulder joint.