Glenohumeral Joint (Full Capsular Volume)

articulatio humeri (capacitas capsularis)

The glenohumeral joint sacrifices stability for mobility. The humeral head is three times larger than the shallow glenoid fossa. This inherent instability is compensated by the rotator cuff (dynamic stabiliser), glenohumeral ligaments (static stabilisers), and the labro-ligamentous complex. Normal joint capsular volume is 10-35 mL; it contracts to 3-5 mL in adhesive capsulitis and expands to >35 mL in multidirectional instability.

Anatomical Data

Structure

Bones	Humeral head (large ball, covers only 30% of its articular surface on the glenoid at any given position) Glenoid fossa (shallow, only 25-30% of the humeral head diameter in contact) Labrum (deepens the glenoid by 50% to increase congruence)
Ligaments	SGHL, MGHL, IGHL (anterior and posterior bands) Coracohumeral ligament Posterior capsule

Biomechanics

Function & Actions

Movements	Flexion 180 degrees Extension 60 degrees Abduction 180 degrees Adduction 30-45 degrees Internal rotation 90 degrees (shoulder at 90 abduction) External rotation 90 degrees

Clinical Relevance

Clinical Notes

Shoulder instability direction determines surgical approach: anterior instability (Bankart + MPFL reconstruction for labral tears; Latarjet coracoid transfer for bone loss >20-25%); posterior instability (posterior labral repair); multidirectional instability (capsular shift). The glenoid bone loss percentage determines whether soft tissue repair alone is sufficient.

Pathology

Common Injuries & Conditions

Anterior Shoulder Instability

Bankart lesion with labral detachment treated by arthroscopic Bankart repair; glenoid bone loss >25% requiring Latarjet coracoid transfer.

Explore

More in Shoulder

Browse all of Shoulder →