Shoulder anatomy
The shoulder is not a single joint, but a complex arrangement of bones, ligaments, muscles and tendons, providing strength and motion to the arm. The joint capsule, a watertight sac surrounding the joint, is formed by a group of ligaments that connect the humerus to the glenoid. The glenohumeral ligaments (GHL) provide the shoulder’s main source of stability, holding it in place and keeping it from dislocating. Collectively the supraspinatus, infraspinatus, teres minor and subscapularis muscles form the rotator cuff. The rotator cuff is a group of muscles which work together to provide the glenohumeral joint with dynamic stability, helping to control the joint during rotation.
The acromio-clavicular joint (ACJ) forms the junction between the collar bone (clavicle) and the top of the shoulder blade (acromium). The ACJ plays an important role in transmitting forces through the upper limb and shoulder to the axial skeleton (the body’s central axis). The ACJ has only minimal mobility though due to its supporting ligaments – the acromio-clavicular ligament and the coraco-clavicular ligament. The acromio-clavicular ligament restricts movement forwards and backwards. The coraco-clavicular ligament plays an important role in keeping the shoulder 'square'. They are extremely strong and support a heavy load.
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Acknowledgements:
* Link to www.shoulderdoc.co.uk courtesy of Prof. L Funk, Consultant Shoulder & Upper Limb Surgeon, Wrightington Hospital.
Important: The information and guidance provided here is general in nature and should not be considered as medical advice in any way. You should always seek detailed advice from a qualified medical practitioner.
