This exhibit depicts the coronal anatomy of a shoulder with impingement syndrome, and the mechanism of impingement during abduction. Anatomical structures include: the clavicle, acromion, subacromial bursa, supraspinatus, labrum, glenoid fossa, humeral head, and scapula. During abduction, the supraspinatus contracts to raise the arm. As the subacromial bursa attempts to glide beneath the acromioclavicular joint, it is pinched by degenerative bone spurs on the inferior aspect of the clavicle and acromion. This can result in pain and weakness of the shoulder joint.