The glenohumeral, or shoulder, joint is a synovial joint that attaches the upper limb to the axial skeleton. It is a ball-and-socket joint, formed between the glenoid fossa of scapula (gleno-) and the head of humerus (-humeral). Acting in conjunction with the pectoral girdle, the shoulder joint allows for a wide range of motion at the upper limb; flexion, extension, abduction, adduction, external/lateral rotation, internal/medial rotation and circumduction. In fact, it is the most mobile joint of the human body. This shoulder function comes at the cost of stability however, as the bony surfaces offer little support. Instead the surrounding shoulder muscles and ligamentous structures offer the joint security; the capsule, ligaments and tendons of the rotator cuff muscles. Because of this mobility-stability compromise, the shoulder joint is one of the most frequently injured joints of the body.