Ligaments of the Shoulder (Glenohumeral) Joint

Anatomy Diagrams

1. Glenohumeral Ligaments (GHLs)

A. Superior Glenohumeral Ligament (SGHL)

• Origin: Anterosuperior glenoid rim, conjoined with the biceps labral anchor
• Insertion: Proximal edge of the lesser tubercle / intertubercular groove
• Orientation: Runs nearly horizontal, parallel to the biceps tendon, almost perpendicular to the MGHL
• Function: Limits inferior translation and external rotation of the adducted shoulder (taut at 0° abduction); together with the coracohumeral ligament, it forms the biceps pulley in the rotator interval
• Note: Absent in 3-10% of healthy subjects

B. Middle Glenohumeral Ligament (MGHL)

• Origin: Upper margin of the glenoid cavity / glenoid neck
• Insertion: Anatomic neck of the humerus
• Orientation: Passes at almost a right angle to the subscapularis tendon insertion
• Function: Limits external rotation and anterior translation at 45-60° abduction
• Clinical note: Highly variable - the Buford complex involves a cord-like MGHL with congenital absence of the anterosuperior labrum (seen in ~1.5-2% of individuals)

C. Inferior Glenohumeral Ligament (IGHL)

• Origin: Inferior glenoid rim and labrum (anteromedial aspect)
• Insertion: Distal lesser tubercle and proximal humeral shaft
• Structure: Has three components - an anterior band (AB-IGHL), a posterior band (PB-IGHL), and an intervening axillary recess/pouch between the two bands
• Function: The primary restraint to anterior, posterior, and inferior translation with the arm in abduction (90°). Acts as a hammock during abduction; the anterior band is the most important restraint to anterior glenohumeral dislocations
• Clinical significance: The AB-IGHL is the most commonly injured ligament in anterior shoulder dislocations (Bankart lesion)

2. Coracohumeral Ligament (CHL)

• Origin: Base/lateral border of the coracoid process (broad, strong band)
• Insertion: Two slips go to the greater and lesser tubercles of the humerus (bridges the rotator interval)
• Function:
  • Stabilizes the long head of the biceps tendon as it passes through the intertubercular groove (forms the roof of the biceps pulley with the SGHL)
  • Together with the SGHL, limits inferior translation and external rotation of the adducted arm
  • Reinforces the capsule superiorly
• Rotator interval: The CHL and SGHL together form the rotator interval - the capsular gap between the anterior edge of supraspinatus and the superior edge of subscapularis. Rotator interval closure reduces external rotation in adduction and posteroinferior translation.

3. Coracoacromial Ligament (CAL)

• Origin: Undersurface of the medial acromion
• Insertion: Superolateral border of the coracoid process
• Function: Acts as a tension band supporting the acromion and coracoid; forms the coracoacromial arch (along with acromion and coracoid process) which serves as a roof over the subacromial space. It limits upward displacement of the humeral head and transmits force from surrounding muscles.
• Clinical note: The CAL is not a true joint ligament but is functionally important; it is the primary structure involved in subacromial impingement. Its integrity becomes even more critical after acromioplasty.

4. Transverse Humeral Ligament

• Attachment: Bridges the greater and lesser tubercles of the humerus across the intertubercular (bicipital) groove
• Function: Acts as a retinaculum, holding the tendon of the long head of biceps brachii in the intertubercular groove, preventing it from subluxing medially

Summary Table

Functional Correlation: Position-Dependent Stability

• 0° (adduction): SGHL + CHL are taut
• 45-60° abduction: MGHL becomes taut
• 90° abduction: IGHL (especially anterior band) becomes the primary restraint