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Inferior glenohumeral ligament, axillary pouch

The inferior glenohumeral ligament (IGHL) is the primary static stabilizer of the shoulder joint in abduction and external rotation. Its axillary pouch, a hammock-like recess of the joint capsule, forms the most inferior portion of the glenohumeral capsule and is critical in preventing anterior and posterior dislocation when the arm is elevated.

The axillary pouch serves as a redundant fold of capsule that unfolds during abduction to allow free movement without tension, while tightening at extremes of motion to maintain humeral head congruency. It is commonly involved in shoulder instability, adhesive capsulitis, and capsular injuries.

Synonyms

  • Inferior capsular recess of shoulder joint

  • Axillary recess of glenohumeral capsule

  • IGHL pouch

Location and Structure

  • The axillary pouch represents the inferior portion of the glenohumeral joint capsule, connecting the anterior and posterior bands of the IGHL.

  • Shape: Redundant, pouch-like fold extending inferiorly between the glenoid and humeral neck.

  • Attachments:

    • Medially: Inferior glenoid rim and adjacent labrum.

    • Laterally: Anatomic neck of the humerus below the articular cartilage margin.

  • Composition: Dense fibrous tissue continuous with the capsule, lined by synovium.

  • Orientation: Lies within the axillary recess, accommodating humeral translation during elevation.

Relations

  • Superiorly: Middle glenohumeral ligament and humeral head.

  • Inferiorly: Axillary fold and subscapularis recess.

  • Anteriorly: Anterior band of IGHL and subscapularis tendon.

  • Posteriorly: Posterior band of IGHL and teres minor tendon.

  • Medially: Inferior glenoid labrum.

  • Laterally: Inferior humeral neck and capsule insertion.

Nerve Supply

  • Articular branches from the axillary nerve and suprascapular nerve supplying the inferior capsule and labrum.

Function

  • Static stabilization: Primary restraint against anterior and posterior humeral head translation when the shoulder is abducted ≥90°.

  • Capsular compliance: Provides slack for full shoulder abduction and rotation without tension.

  • Reinforcement: Integrates with the anterior and posterior IGHL bands to form a supportive capsular hammock.

  • Load distribution: Dissipates joint stress during overhead and throwing motions.

  • Protective role: Prevents inferior subluxation in the dependent arm position.

Clinical Significance

  • Shoulder instability: Anterior band and axillary pouch often torn in Bankart or HAGL (humeral avulsion of glenohumeral ligament) lesions.

  • Adhesive capsulitis (frozen shoulder): Thickening and contraction of the axillary pouch restricts motion.

  • Capsular injury: Stretching or detachment may accompany anterior dislocation.

  • Capsulolabral complex tears: Involve axillary pouch insertion on glenoid labrum.

  • Postoperative assessment: MRI and CT arthrography help evaluate repair integrity and capsular laxity.

MRI Appearance

  • T1-weighted images:

    • Capsule and ligament: Low signal (dark band) outlining the inferior joint recess.

    • Synovial fluid within pouch: Bright, delineating the fold.

    • Marrow of humeral head and glenoid: Bright due to fatty content.

    • Thickened or contracted pouch: Low-signal broad band replacing normal thin fold.

  • T2-weighted images:

    • Capsule and ligament: Low signal (dark band) 

    • Normal pouch: Intermediate-to-bright signal fluid-filled recess between low-signal capsular walls.

    • Thickening or fibrosis: Low signal, irregular contour.

    • Effusion or capsular distension: Bright hyperintense fluid outlining inferior capsule.

    • HAGL lesion: Disruption of capsule attachment to humeral neck with focal fluid extravasation.

  • STIR:

    • Normal capsule: Intermediate-to-dark.

    • Pathology (edema, inflammation): Bright hyperintense thickened axillary fold.

    • Excellent for detecting capsular edema in adhesive capsulitis.

  • Proton Density Fat-Saturated (PD FS):

    • Capsule: Intermediate-to-dark signal intensity.

    • Fluid or edema: Bright hyperintense areas between capsule and humeral neck.

    • Distension, thickening, or tear visualized as abnormal bright signal disrupting continuity.

  • T1 Fat-Sat Post-Contrast:

    • Normal capsule: Thin, smooth low-signal outline with minimal enhancement.

    • Adhesive capsulitis: Intense enhancement of axillary pouch and rotator interval capsule.

    • Capsular tear or avulsion: Focal enhancement with irregular margins or capsular gap.

    • Postoperative scarring: Heterogeneous enhancement along inferior capsule.

CT Appearance

Non-Contrast CT:

  • Capsule and ligament: Appear as thin, soft-tissue density inferior to humeral head.

  • Joint space: Low attenuation due to synovial fluid.

  • Calcification or ossification: May be seen in chronic inflammation or post-surgery.

  • Fractures or avulsions: Bony HAGL lesions may show small cortical avulsion at humeral neck.

Post-Contrast CT (standard):

  • Capsule and pouch: Enhanced definition of capsule and synovium.

  • Adhesive capsulitis: Thickened inferior capsule with enhancing fibrosis.

  • HAGL or capsular tear: Contrast extravasation from joint into adjacent soft tissues.

  • CT arthrography: Shows contrast filling the axillary recess, defining capsule contour and detecting subtle tears or adhesions.

MRI image

Inferior Glenohumeral Ligament Axillary pouch axial cross sectional anatomy 3T MRI AI enhanced radiology image-img-00000-00000

MRI image 1mm

Inferior glenohumeral ligament posterior band mri 1mm axial