glenohumeral

The glenohumeral joint, commonly referred to as the shoulder joint, is the articulation between the head of the humerus and the glenoid fossa of the scapula. The glenoid rim is deepened by the glenoid labrum, which helps stabilize the joint by increasing the socket depth. The articular surfaces are covered with hyaline cartilage, and the joint is enclosed by a loose fibrous capsule lined with synovium. The capsule is reinforced by various ligaments and tendons that contribute to stability while permitting a wide range of motion.

Stability of the glenohumeral joint is provided by both static and dynamic structures. The glenohumeral ligaments (superior, middle, and inferior) strengthen the anterior capsule, while the coracohumeral ligament reinforces the superior aspect. The glenoid labrum forms a suction seal that helps keep the head of the humerus centered within the socket. Dynamic stability is supplied by the rotator cuff tendons—supraspinatus, infraspinatus, teres minor, and subscapularis—as well as the long head of the biceps. Blood supply largely comes from the circumflex humeral arteries, and the axillary and suprascapular nerves contribute to innervation.

Biomechanically, the glenohumeral joint is a ball-and-socket joint with an extensive range of motion, including flexion, extension, abduction, adduction, and internal/external rotation. Its stability relies on a balance between passive structures (capsule, ligaments, labrum) and active stabilizers (rotator cuff and other muscles). The joint’s mobility makes it susceptible to injuries and instability.

Clinically, the joint is prone to dislocations (most commonly anterior), labral tears such as Bankart lesions, and humeral head impression lesions like Hill–Sachs. Other conditions include rotator cuff tears, adhesive capsulitis (frozen shoulder), and osteoarthritis. Diagnosis combines physical examination and imaging (X-ray, MRI or MR arthrography). Treatment ranges from conservative therapy with physical rehabilitation to surgical repair or arthroscopy as indicated.