Calcification in supraspinatus tendon

Use of ultrasound to identify the source of painful shoulder snapping. The image shows an S-shaped calcification (arrows) within and deforming the supraspinatus tendon in a patient presenting with pain and shoulder snapping. The large calcification was snapping in and out of the subacromial space during arm motion. DELT, middle deltoid muscle; HUM, humeral head.