The rotator cuff muscles originate from the scapula, known as the "wing bone." Three of these muscles form a single tendon unit as they attach to the humeral head. The space between the rotator cuff and the upper bone of the shoulder (the acromion) is filled by a sac of fluid called the bursa. It is the balloon-like bursa that allows muscles to glide freely when moving, and is commonly irritated or inflamed in rotator cuff injury. Rotator cuff tears are diagnosed by physical exam, x-ray, MR, arthrography or ultrasound exams.
The symptoms
- Gradual weakening of the muscles around the shoulder over time
- Pain when lifting the arm
- Weakness when lifting or rotating the arm
- Cracking sensation when moving the shoulder in certain positions
- Pain when lying on affected side at night (known as night pain)
