The shoulder is a complex, highly mobile joint designed to provide the highest amount of motion of any joint in the body. One part that frequently see stress is the biceps tendon. The biceps muscle is on the front of the upper arm and attaches to various parts of the upper arm and shoulder. When we refer to biceps tendonitis in the shoulder, we are most often referring to the long head of the biceps brachii. This tendon runs up the front of the arm, over top of the humeral head, and attaches on the shoulder labrum and glenoid, or socket of the shoulder joint.
Most often this injury is due to overuse, especially with repetitive activity in specific positions. Over time, the tendon sustains forces that exceeds its capacity leading to micro-injuries. You may not notice these at first, but given enough time, the tendon starts having larger tears, gets thick and swollen, and inflammation settles in causing pain and decreased function.
Occasionally, a single traumatic event can occur injuring the tendon, even causing a tendon rupture.
Additional risk factors of biceps tendonitis include: