GLOSSARY

The shoulder (glenohumeral) joint is the ball-and-socket joint between the head of the humerus and the glenoid cavity of the scapula and is the most mobile joint in the body.

Stabilising Structures

• Static (passive): the glenoid labrum, joint capsule, superior, middle, and inferior glenohumeral ligaments, the coracohumeral ligament, and negative intra-articular pressure.
• Dynamic (active): the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis), which keep the humeral head “centred” in the socket, the long head of biceps tendon, and the scapular stabilisers.

Movements

Flexion to about 180 degrees (with the scapula), extension, abduction, adduction, internal and external rotation, and circumduction.

Relevance to Sport

• Anterior dislocation: over 95 percent of shoulder dislocations, usually with the arm in abduction and external rotation, as in tackling or blocking in handball; under the age of 20, the risk of recurrence is very high.
• Rotator cuff injuries and tendinopathy: in swimmers, tennis players, and throwers.
• Thrower’s shoulder: increased external rotation and reduced internal rotation; prevention programmes such as external rotator strengthening and scapular control reduce injury risk.