Bursitis (inflammation of a bursa) often occurs along with tendonitis and/or impingement syndrome. A bursa is a sac (containing a small amount of fluid) located between the tendon and bone that helps the moving parts of a joint glide smoothly. There is a bursa between the supraspinatus (a rotator cuff tendon) and acromion (roof of shoulder blade). Occasionally, calcium deposits or bone spurs may be present within the rotator cuff tendon(s) or the underside of the acromion. This can also cause impingement syndrome.