Shoulder sonography has been shown to be an effective noninvasive means of detecting rotator cuff tears and biceps tendon abnormalities. The examination requires careful attention to technique and a thorough knowledge of normal gross and sonographic anatomy. Rotator cuff tears generally cause a diffuse or focal decrease in the space between the humeral head and the deltoid muscle. Therefore, tears are easiest to detect by noting abnormally close apposition of the deltoid and humeral head.