Fractures of the shoulder girdle. Shoulder joint dislocation
The bones of the shoulder girdle are:
- Clavicle
- S shaped bone that forms the sternoclavicular joint and acromioclavicular joint
- The middle ⅓ is the narrowest with no muscle insertions, clavicle widens laterally
- This is the most commonly fractured bone in the body
- Clavicle holds an angle of 60 degrees
- Scapula
- Flat triangular bone with spine posteriorly that separates the supra and infraspinous fossa
- Contains the coracoid process anteriorly, the acromion laterally, and the glenoid
- Humerus (discussed below)
Important joints are:
- Sternoclavicular joint (allows for increased range of scapula motion - 60 degrees rotation)
- Acromioclavicular joint (allows rotation between the scapula and clavicle - 60 degrees)
- *Glenohumeral joint (allows adduction, abduction, medial and lateral rotation, flexion and extension)
- Scapulocostal joint (musculotendinous joint)
- Suprahumeral joint (coracoacromial lg and head of the humerus, plays a role in complex movements when the arm is fully flexed)
*Glenohumeral joint is the shoulder joint, not technically part of the shoulder girdle
Range of movement of the shoulder girdle is:
- Elevation - depression - 40-0-10 degrees
- Protraction - retraction - 25-0-25 degrees
Range of movement of the shoulder joint alone:
- Abduction - adduction - 90-0-40 degrees
- Anteversion - retroversion - 90-0-40 degrees
- External rotation - internal rotation - 60-0-70 degrees
Range of movement shoulder + shoulder girdle:
- Abduction - adduction - 180-0-40 degrees
- Anteversion - retroversion - 170-0-40 degrees
- External rotation - internal rotation - 90-0-100 degrees
Important ligaments:
- Sternoclavicular joint
- Sternoclavicular anterior
- Costoclavicular ligament
- Interclavicular ligament
- Acromioclavicular joint
- Acromioclavicular ligament
- Coracoclavicular ligament - trapezius
- Coracoclavicular ligament - conoideum
- Glenohumeral joint
- Tendon of the long head of biceps brachii
- Glenohumeral ligament (superior, middle and inferior)
- Coracohumeral joint
- Roof of shoulder = ligaments of acromioclavicular joint
The muscles that contribute to the movement of the shoulder joint are divided into a number of different groups:
- Periscapular
- Trapezius (CN XI)
- Latissimus dorsi (Thoracodorsal)
- Levator scapulae (Dorsal scapula)
- Rhomboid minor (Dorsal scapula)
- Rhomboid minor (Dorsal scapula)
- Rhomboid major (Dorsal scapula)
- Rotator cuff
- Supraspinatus (Suprascapular)
- Infraspinatus (Suprascapular)
- Teres minor (Axillary)
- Subscapularis (upper and lower subscapular)
- Deltopectoral
- Deltoid (Axillary)
- Pectoralis major (medial and lateral pectoral)
- Pectoralis minor (medial pectoral)
- Serratus anterior (long thoracic)
- Subclavius (nerve to subclavius)
Clinically, there are some valuable questions we can ask regarding the nature of the symptoms for a patient. History will help us elucidate where the issue could be.
- Age
- Old - rotator cuff tear, impingement, arteritis, adhesive capsulitis, humeral fracture