As its name suggests, the biceps muscle consists of two muscle heads (Latin ‘Bi’ for two). It has two tendons (short and long), each of which originates at a different point on the scapula. The long biceps tendon originates at the upper glenoid rim of the shoulder joint, passes through a pit in the humerus (sulcus bicipitalis), and finds its base at the radius. The biceps functions as an arm flexor muscle and is the most critical external rotator of the forearm when the elbow is flexed (supinator, e.g., when tightening a screw).
The long biceps tendon can be affected by several health problems.