Glenohumeral Ligaments

The glenohumeral ligaments are a group of three intrinsic ligaments located within the shoulder joint capsule. They provide anterior reinforcement to the glenohumeral joint, the main articulation between the scapula and humerus. These ligaments are essential for maintaining joint stability, especially during movements that place stress on the anterior capsule, such as abduction and external rotation.

Types

There are three glenohumeral ligaments:

• Superior glenohumeral ligament (SGHL)
• Middle glenohumeral ligament (MGHL)
• Inferior glenohumeral ligament (IGHL) with anterior and posterior bands and an axillary pouch

Location

Structure

• All three ligaments are thickenings of the fibrous joint capsule of the shoulder.
• They are poorly defined in some individuals and may appear as folds within the synovial lining during arthroscopy.
• The inferior glenohumeral ligament complex is the most important stabilizer and has a hammock-like structure with distinct anterior and posterior bands.

Function

• SGHL: Prevents inferior translation of the humeral head when the arm is at rest or in slight abduction.
• MGHL: Resists anterior translation and external rotation of the arm, especially between 45 and 60 degrees of abduction.
• IGHL: Acts as the primary stabilizer in the abducted and externally rotated shoulder (throwing position), preventing anterior dislocation.

Physiological Role(s)

• Maintain passive stability of the glenohumeral joint throughout its wide range of motion.
• Reinforce the anterior joint capsule and coordinate with the labrum, capsule, and rotator cuff for dynamic stability.
• Help prevent excessive translation or rotation that could lead to impingement, strain, or dislocation.

Relations

• Anteriorly: Subscapularis muscle lies superficial to the capsule and ligaments.
• Posteriorly: Infraspinatus and teres minor provide posterior reinforcement.
• Superiorly: The coracohumeral ligament and long head of the biceps tendon share proximity with the SGHL.

Development

The glenohumeral ligaments form from mesenchymal condensations within the developing shoulder joint capsule. They are present by the second trimester and mature in structure by late gestation. Their final length, orientation, and thickness are shaped postnatally by mechanical forces, muscle activity, and shoulder movement patterns.

Clinical Significance

• Shoulder dislocation: Injury to the IGHL, especially the anterior band, is commonly associated with anterior shoulder dislocation and Bankart lesions.
• Capsular laxity: In overhead athletes or individuals with generalized ligamentous laxity, attenuation of glenohumeral ligaments may contribute to instability or subluxation.
• Frozen shoulder (adhesive capsulitis): Contracture of the capsule including the glenohumeral ligaments restricts range of motion and causes pain.
• Arthroscopic repair: Surgical reconstruction or plication of torn glenohumeral ligaments may be required in chronic instability cases.

Imaging

• MRI: Best modality for visualizing ligament integrity, especially with intra-articular contrast (MR arthrogram).
• Arthroscopy: Allows direct inspection of the glenohumeral ligaments during joint evaluation or surgery.
• Ultrasound: Not suitable for assessing intra-articular ligaments due to depth and orientation.

Anatomical Variations

• The MGHL may be absent in a small percentage of individuals or may appear as a cord-like or fan-shaped structure.
• The SGHL and coracohumeral ligament may form a conjoined ligament in some cases.
• IGHL morphology varies, with some individuals having a more prominent anterior band and others a well-developed axillary pouch.