The transverse humeral ligament acts as a seatbelt for your biceps tendon.

The transverse humeral ligament (THL) is a narrow band of connective tissue that bridges the gap between the greater and lesser tubercles of the humerus. This anatomical structure converts the intertubercular groove into a canal, effectively housing the long head of the biceps brachii tendon. Its primary mechanical role is to act as a retinaculum, providing stability and preventing medial dislocation of the tendon during rotational movements of the shoulder.Research published in the Journal of Shoulder and Elbow Surgery highlights that while the THL is often considered a distinct ligament, it is actually composed of fibers from the subscapularis and supraspinatus tendons. This complex network ensures that the biceps tendon remains centered within its groove even under significant tension. When this 'seatbelt' is torn or weakened, a condition known as biceps tendon subluxation occurs, which can lead to chronic pain and a clicking sensation in the shoulder joint.Clinical studies indicate that injuries to this region are frequently associated with rotator cuff tears, particularly involving the subscapularis muscle. Orthopedic surgeons often evaluate the integrity of this ligament using MRI or ultrasound to diagnose shoulder instability. Maintaining the health of this small structure is vital for athletes and weightlifters who perform repetitive overhead motions or heavy lifting, as it ensures the biceps can generate force efficiently without slipping out of alignment.