Glenohumeral Ligament: Anatomy, Function, Imaging

Topic

Glenohumeral ligaments

The glenohumeral ligaments (GHLs) are three distinct capsular thickenings of the shoulder joint capsule that reinforce the anterior aspect of the glenohumeral (shoulder) joint. They stabilize the humeral head within the glenoid cavity, particularly during extremes of motion. These ligaments are essential for joint stability, preventing anterior dislocation, and controlling humeral head translation during abduction and external rotation.

The three components are the superior (SGHL), middle (MGHL), and inferior (IGHL) glenohumeral ligaments, each arising from the glenoid margin or labrum and inserting along the anatomical neck of the humerus. Together, they form a key part of the capsulolabral complex of the shoulder.

Synonyms

GH ligaments
Capsular ligaments of the shoulder joint
Anterior capsular complex

Location and Structure

Number: Three distinct bands — superior, middle, and inferior glenohumeral ligaments.
Origin: Anterior margin of the glenoid cavity and adjacent glenoid labrum.
Insertion: Anatomical neck of the humerus and adjacent joint capsule.
Type: Intracapsular but extrasynovial ligaments (thickenings of joint capsule).

1. Superior Glenohumeral Ligament (SGHL):

Originates from the upper pole of the glenoid near the supraglenoid tubercle and base of the coracoid process.
Inserts on the upper part of the lesser tubercle of the humerus.
Function: Limits inferior translation of the humeral head when the arm is adducted.

2. Middle Glenohumeral Ligament (MGHL):

Arises from the anterior glenoid rim and labrum.
Inserts on the anterior aspect of the humeral neck, deep to the subscapularis tendon.
Function: Limits external rotation and anterior translation of the humeral head at mid-abduction.

3. Inferior Glenohumeral Ligament (IGHL) Complex:

The strongest and most important stabilizer.
Originates from the anteroinferior glenoid rim and labrum; inserts on the inferior humeral neck.
Composed of anterior and posterior bands with an interposed axillary pouch.
Function: Primary restraint to anterior and posterior translation in abduction and external rotation; resists inferior displacement.

Relations

Anteriorly: Subscapularis tendon and biceps long head tendon (superiorly).
Posteriorly: Glenoid cavity and joint capsule.
Superiorly: Coracohumeral ligament and rotator cuff tendons.
Inferiorly: Axillary recess of the joint capsule.
Laterally: Anatomical neck of the humerus.

Nerve Supply

Articular branches from the axillary nerve and suprascapular nerve supply the capsule and its ligamentous thickenings.

Function

Joint stability: Prevents anterior, posterior, and inferior displacement of the humeral head.
Capsular reinforcement: Strengthens the anterior joint capsule.
Dynamic control: Works with rotator cuff tendons to maintain centering of the humeral head.
Movement limitation: Restrains excessive external rotation and abduction.
Pathomechanics: IGHL is the most important structure preventing anterior shoulder dislocation.

Clinical Significance

Capsulolabral injuries: Common in shoulder dislocations and subluxations.
Bankart lesion: Detachment of the IGHL-labrum complex from the glenoid.
HAGL lesion (Humeral Avulsion of Glenohumeral Ligament): Avulsion of the IGHL from its humeral attachment, seen in traumatic instability.
Capsular laxity: Seen in multidirectional shoulder instability.
Degeneration or fibrosis: Occurs in adhesive capsulitis (“frozen shoulder”).
Imaging relevance: MRI and MR arthrography are gold standards for evaluating GH ligament tears, avulsions, and capsular abnormalities.

MRI Appearance

T1-weighted images:
- Ligaments: Low signal (dark linear bands) representing dense collagen fibers.
- Marrow (humerus and glenoid): Bright fatty signal.
- Cartilage: Intermediate signal over articular surfaces.
- Joint capsule: Low signal; thickened in capsulitis or fibrosis.
- Pathology: Disruption or irregular contour indicates partial or full-thickness ligament tear.
T2-weighted images:
- Ligaments: Low signal with sharp margins.
- Pathology: Partial tears show focal bright signal; complete tears show discontinuity or retraction with joint effusion.
- IGHL complex: Best visualized in abduction–external rotation (ABER) position, appearing as taut linear bands.
- Capsulitis: Thickened capsule with mild pericapsular hyperintensity.
STIR:
- Normal ligament: Dark (low signal).
- Inflamed or injured ligament: Bright hyperintense signal within fibers or surrounding capsule (edema, strain).
- Excellent for early detection of HAGL or capsular edema.
Proton Density Fat-Saturated (PD FS):
- Normal: Ligament appears dark and continuous.
- Partial tear: Bright hyperintense signal within low-signal band.
- Complete tear: Discontinuity or non-visualization with fluid gap.
- Best sequence for assessing subtle capsular-labral complex injuries.
T1 Fat-Sat Post-Contrast:
- Normal capsule and ligaments: Minimal enhancement.
- Capsulitis: Diffuse capsular enhancement.
- HAGL lesion: Enhancing pericapsular soft tissue with fluid-filled defect at humeral neck.
- Postoperative or chronic scarring: Peripheral enhancement with central low-signal fibrosis.

CT Appearance

Non-Contrast CT:

Ligaments: Not well visualized directly (soft-tissue density).
Indirect signs: Joint space widening, humeral head subluxation, or cortical avulsion fragment at humeral neck (HAGL).
Bone morphology: Glenoid and humeral head alignment easily assessed.

Post-Contrast CT (CT Arthrography):

Contrast outlines capsule and ligament recesses.
Tears: Appear as contrast extravasation beyond the expected capsule contour.
HAGL lesion: Contrast tracks along humeral neck with extravasation inferiorly.
Excellent for detecting capsular avulsion, labral tears, and capsular recess distension when MRI is contraindicated.

MRI images

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