Inferior Glenohumeral Ligament: Anatomy, Function, Imaging

Topic

Inferior glenohumeral ligament

The inferior glenohumeral ligament (IGHL) is the primary static stabilizer of the shoulder joint, especially in abduction and external rotation. It forms the inferior part of the glenohumeral joint capsule and plays a crucial role in preventing anterior and posterior dislocation of the humeral head.

Anatomically, the IGHL is a complex capsuloligamentous structure consisting of three components:

Anterior band
Posterior band
Axillary pouch (connecting them inferiorly)

Together, these structures create a hammock-like sling that supports the humeral head during overhead movement. Injury to the IGHL is a key feature in shoulder instability syndromes, such as Bankart and HAGL (humeral avulsion of the glenohumeral ligament) lesions.

Synonyms

Inferior glenohumeral ligament complex
IGHL complex
Inferior capsuloligamentous band of shoulder

Location and Structure

Position: Inferior aspect of the glenohumeral joint capsule, spanning from the inferior glenoid labrum to the anatomic neck of the humerus.
Components:
- Anterior band: Extends from the anterior-inferior glenoid margin to the inferior-anterior humeral neck.
- Posterior band: Runs from the posterior-inferior glenoid margin to the inferior-posterior humeral neck.
- Axillary pouch: Thin, redundant inferior capsule connecting the two bands; deepens during abduction.
Shape: Forms a hammock or U-shaped sling beneath the humeral head.
Composition: Dense fibrous connective tissue continuous with the joint capsule and the glenoid labrum.

Relations

Superiorly: Middle glenohumeral ligament and inferior capsule of the joint.
Inferiorly: Axillary recess of the joint capsule and axillary pouch.
Anteriorly: Subscapularis tendon and anterior capsule.
Posteriorly: Long head of triceps tendon and posterior capsule.
Medially: Glenoid labrum and inferior glenoid rim.
Laterally: Anatomic neck of humerus and articular cartilage.

Attachments

Medial (glenoid) attachment: Inferior glenoid rim and adjacent labrum.
Lateral (humeral) attachment: Inferior aspect of the anatomic neck of the humerus, blending with the joint capsule.
Continuous with: Inferior capsule, glenoid labrum, and articular synovium.

Nerve Supply

Articular branches of the axillary nerve and suprascapular nerve supply proprioceptive and nociceptive fibers to the inferior capsule and IGHL complex.

Function

Primary stabilizer: Prevents inferior translation of the humeral head in abduction.
Anterior band: Restrains anterior translation in abduction and external rotation.
Posterior band: Restrains posterior translation in abduction and internal rotation.
Axillary pouch: Deepens to cradle the humeral head, maintaining stability during elevation.
Dynamic support: Works synergistically with rotator cuff and labrum to stabilize the shoulder through full range of motion.

Clinical Significance

IGHL injuries: Common in anterior shoulder dislocations, especially with abduction–external rotation mechanisms.
Bankart lesion: Detachment of IGHL–labral complex from anterior glenoid.
HAGL lesion: Humeral avulsion of the IGHL, may be anterior (aHAGL) or posterior (pHAGL).
Adhesive capsulitis: IGHL thickening and contracture limit shoulder abduction.
Instability testing: Laxity or tears demonstrated on MR arthrography.
Surgical relevance: Repaired in capsulolabral reconstructions and instability repairs.

MRI Appearance

T1-weighted images:
- IGHL bands: Low signal (dark fibrous tissue) surrounding the inferior joint capsule.
- Marrow: Bright signal within adjacent humeral and glenoid bone.
- Capsular contour: Smooth in normal state, thickened or irregular with capsulitis or scarring.
- HAGL lesions: Discontinuity or irregular low-signal fibers detached from humeral neck.
T2-weighted images:
- Normal ligament: Low signal intensity, sharply defined.
- Axillary pouch: Intermediate-to-bright signal due to joint fluid; distends with abduction.
- Pathology:
  - IGHL tear: Focal discontinuity or retraction with surrounding bright edema.
  - Capsular thickening: Intermediate-to-bright signal in adhesive capsulitis.
  - HAGL lesion: Bright fluid between humeral neck and detached ligament fibers.
STIR:
- Normal ligament: Intermediate-to-dark signal.
- Injury or inflammation: Bright hyperintense due to fluid or edema around torn fibers.
- Excellent for early detection of HAGL or capsular strain.
Proton Density Fat-Saturated (PD FS):
- Normal: Intermediate-to-dark ligament bands against bright joint fluid.
- Abnormal: Hyperintense signal with partial disruption or frayed fibers.
- Highlights edema, capsular effusion, and periligamentous changes.
T1 Fat-Sat Post-Contrast:
- Normal: Mild uniform enhancement of capsule and synovial lining.
- Pathologic: Focal or linear enhancement in capsulitis or labroligamentous inflammation.
- Post-traumatic: Enhancement surrounding detached ligament margins or at the labral interface.

CT Appearance

Non-Contrast CT:

Ligament: Not directly visualized due to low attenuation of soft tissue.
Indirect signs: Joint effusion, cortical irregularity at humeral neck (HAGL), or glenoid rim fracture (Bankart).
Useful for: Assessing bone defects, Hill–Sachs lesions, and glenoid morphology.

Post-Contrast CT (CT Arthrography):

IGHL pouch: Outlined by intra-articular contrast; appears as a smooth inferior recess in normal cases.
IGHL tear: Contrast extravasation beneath humeral neck (crescent sign) or into soft tissues (HAGL).
Labral detachment: Contrast interposes between labrum and glenoid rim (Bankart).
Adhesive capsulitis: Reduced capsular distension and thickened inferior capsule.

MRI images

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