The Shoulder (Glenohumeral) Joint

ball and socket joint biceps tendon corahumeral ligament glenohumeral joint glenoid labrum labrum rotator cuff tendons shoulder joint subacromial bursa

The Shoulder Joint Genohumeral Physiotherapy Solihull Simon Evans

Articular Surfaces

  • Class - Synovial, Ball & Socket joint
  • Close packed in abduction/lateral rotation|
  • Articular Surfaces
    • Hemispherical head of humerus
    • Orientated superiorly (140º) and posteriorly (30º)
    • Covered in hyaline cartilage
  • Glenoid fossa (cavity)
    • Situated on the lateral aspect of scapula
    • Typically pear shaped
    • Covered in hyaline cartilage
    • In anatomical position faces antero-laterally
  • Note difference in size of articular surfaces (size ratio of 1:4) and poor congruence - poor stability

Glenoid Labrum

  • Glenoid fossa  is deepened by the fibrocartilage glenoid labrum – improves size ratio
  • Triangular in X-section 
  • Labrum is complete (compare with acetabular labrum in the hip) 


  • Loose cylindrical sleeve passing from just beyond glenoid articular margins
  • On humerus extends to
    • Anatomical neck and tubercles anteriorly, posteriorly and superiorly
    • Medial shaft of humerus inferiorly
  • Capsule is reinforced posteriorly, anteriorly and superiorly by the tendons of the rotator cuff muscles
  • Note laxity of capsule and inferior fold when arm held in the anatomical position

Opening for Biceps Tendon

  • The capsule is pierced anteriorly to allow the passage of the tendon of the long head of biceps from its origin to the muscle belly 
  • At this point the capsule is thickened by a series of transverse fibres passing from the greater to the lesser tubercle - The Transverse Humeral ligament - to stabilise the tendon


  • The anterior capsule is reinforced anteriorly by 3 weak ligaments 
    • Superior Glenohumeral Joint ligament passes to from the upper part of the glenoid and labrum to just superior to the lesser tubercle
    • Middle Glenohumeral Joint ligament - absent in up to 30% of individuals - passes from the anterior glenoid to just medial to the lesser tubercle
    • Inferior Glenohumeral Joint ligament - passes from the lower glenoid to the neck of the humerus - most important of the 3 ligaments as it tighten in abduction providing inferior stability

Coracohumeral ligament

  • In addition to the 3 Glenohumeral Joint ligaments there is another ligament to consider at the shoulder joint - the coracohumeral ligament
  • Passes from the lateral border of the corocoid process to the greater tubercle (overlies the transverse humeral ligament)
  • Function - to stabilise the dependent arm

Synovial Membrane

  • Lines Capsule:
    • attached to the articular margins of both the glenoid fossa and head of humerus 
  • Note presence of supscapular bursa anteriorly to separate tendon of subscapularis from the anterior margin of the joint (communicating)
  • Also as the long head of biceps passes from its origin under over the head of humerus and in the intertubercular sulcus it is encased in a double layer of synovial membrane

Subacromial Bursa

  • Lies between the deltoid & the coracoacromial arch and the upper end of humerus
  • It is a non-communicating bursa whose function is to allow friction free movement between the humerus/upper rotator cuff tendon and the CA arch

Stability of the Glenohumeral Joint (GHJ)

  • Inherently unstable - poor congruency of articular surfaces, poor size ratio, lax capsule and weak or absent ligaments
  • Stability is increased by 
    • Glenoid labrum
    • Rotator cuff tendons
    • Tendon of long head of biceps
    • Larger muscles overlying joint
  • Stability is predominantly offered by muscles

Surface Markings

  • Anteriorly
    • A line (concave laterally) passing through a point 1cm lateral to the tip of the corocoid porocess
  • Laterally
    • A line passing through the apex of the greater tubercle (concave inferiorly)
  • Ligaments
    • Glenohumeral Joint ligaments  can be identified by finding the surface marking of the shoulder joint - their proximal attachments are just medial to the joint whereas their distal attachments can be found with reference to the lesser tubercle

Movements at the Shoulder Joint

  • When assessing the end of a joint range of motion each movement should have a specific end feel - soft tissue apposition, bony apposition, ligamentous tension, muscular tension
  • Multiaxial joint therefore movements are possible in all 3 planes
  • Flexion - (180) - limited by soft tissue tension (extensors)
  • Extension - (45) - limited by tension in the extracapsular ligaments and shoulder flexors
  • Abduction - (100) - limited by engagement of the greater tubercle into the coracoacromial arch and tension in adductors, inferior part of of capsule and inferior GHJ ligament - if the arm is externally rotated at this point the arm can move through abduction to 180 of elevation
  • Adduction - (45) - limited by soft tissue apposition
  • Medial Rotation - (90) - limited by tension in posterior capsule and lateral rotators
  • Lateral Rotation - (90) - limited by Glenohumeral Joint ligaments, anterior capsule and medial rotators

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