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Anterior glenoid labrum

The anterior glenoid labrum is the fibrocartilaginous rim located along the anterior margin of the glenoid cavity of the scapula. It deepens the socket of the shoulder joint, enhances stability, and provides attachment points for the joint capsule and glenohumeral ligaments.

The anterior portion, particularly the anteroinferior quadrant, is crucial for preventing anterior humeral head translation. It is commonly evaluated in shoulder instability and traumatic injuries such as Bankart lesions.

Synonyms

  • Anterior labrum of glenoid

  • Anterior glenoid rim fibrocartilage

  • Anteroinferior glenoid labrum (specific region)

Location and Structure

  • Positioned along the anterior glenoid rim from the superoanterior to inferoanterior glenoid.

  • Composed of dense fibrocartilage firmly attached to the glenoid.

  • Thicker inferiorly and slightly triangular in cross-section.

  • Continuous with the glenoid capsule, anterior band of the inferior glenohumeral ligament (IGHL), and joint synovium.

Relations

  • Anteriorly: Subscapularis tendon, rotator interval capsule

  • Posteriorly: Glenoid cortex, joint cavity

  • Superiorly: Continuous toward the biceps–labral complex

  • Inferiorly: Anterior band of the IGHL and adjacent capsule

  • Laterally: Humeral head articular surface

  • Medially: Glenoid bone margin

Attachments

  • Firmly attached to glenoid rim via fibrocartilaginous anchoring

  • Provides insertion for the anterior capsulolabral complex

  • Connects to the inferior glenohumeral ligament (anterior band)

  • Superiorly blends with long head of biceps–labral attachment

Function

  • Deepens the glenoid cavity to enhance shoulder stability

  • Acts as an anchoring structure for the anterior capsule and IGHL

  • Prevents anterior subluxation/dislocation of the humeral head

  • Provides a seal effect for the glenohumeral joint, maintaining intra-articular pressure

Clinical Significance

  • Common site of injury in anterior shoulder instability

  • Evaluation target for Bankart variants, ALPSA, Perthes lesions, and capsulolabral tears

  • Important surgical landmark in arthroscopic shoulder repair

  • CT and MRI characterize morphology, attachment integrity, and associated bony changes

MRI Appearance

T1-weighted images:

  • Labrum: Low-to-intermediate signal intensity (fibrocartilage)

  • Glenoid bone marrow: Bright

  • Clear contrast between dark labrum and adjacent fat planes

  • Labral contour appears triangular or rounded depending on region

T2-weighted images:

  • Labrum: Low signal intensity (fibrocartilage remains dark)

  • Joint fluid: Bright, outlining the labral margins

  • Good distinction between labrum and the IGHL anterior band

STIR:

  • Labrum: Low-to-intermediate signal

  • Surrounding fat suppressed; muscle intermediate

  • Highlights subtle edema or increased soft tissue fluid adjacent to labrum

Proton Density Fat-Saturated (PD FS):

  • Labrum: Dark, sharply marginated structure

  • Joint fluid: Bright, outlining labral edges

  • Useful for identifying slight contour irregularities and capsular attachments

CT Appearance

Non-Contrast CT:

  • Labrum itself: Soft tissue density, less conspicuous than cartilage

  • Glenoid rim: Excellent bone detail showing morphology and contour

  • Depicts glenoid bone loss, osseous Bankart, or subtle cortical disruptions

  • Labrum may appear as a thin soft-tissue wedge on the glenoid rim

Post-Contrast CT (Standard):

  • Contrast opacifies joint space (if CT arthrography performed)

  • Labrum remains low-density relative to injected contrast

  • Joint contrast outlines the anterior labral margins clearly

  • Enhances visualization of glenoid rim and capsular attachments

MRI image

Anterior glenoid labrum