The shoulder is usually understood to be the shoulder girdle (including adjacent muscles), which connects both arms to the trunk of the body. The exceptionally large range of motion of the shoulder and arms is partly due to the fact that the shoulder is mainly fixed and moved by muscles - and not by ligaments that are less flexible than the hip joint, for example. However, the structure of the shoulder as a whole and its great mobility also make it particularly susceptible to injury and wear and tear.
Article overview
The main shoulder joint
The actual shoulder joint or main shoulder joint (glenohumeral joint, articulatio humeri) is formed bony from the humeral head (humeral head) and the glenoid ( shoulder socket ), which is part of the shoulder blade (scapula).
It is a ball-and-socket joint in which the humeral head is held in the glenoid cavity by a fibrous cartilage ring (glenoid labrum), the joint capsule, ligaments and, above all, the strong rotator cuff (consisting of muscles and tendons).
As part of the diagnosis of shoulder complaints, these surrounding soft tissues should also be examined(ultrasound, MRI), as they are susceptible to (sports) injuries and signs of wear and tear due to the great mobility of the shoulder.
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The secondary shoulder joints
In addition to the main shoulder joint, secondary shoulder joints are also part of the shoulder girdle:
- the acromioclavicular joint (ACJ ) between the top of the shoulder (acromion) and the outer end of the collarbone (clavicle)
- the sternoclavicular joint between the breastbone (sternum) and the collarbone (clavicle)
- the so-called scapulothoracic joint between the shoulder blade (scapula) and the chest wall (thoracic wall)
- the so-called subacromial joint (more commonly: subacromial space) between the shoulder level (acromion) and the humeral head or the tendon plate serving as the roof of the scapulohumeral joint
The articular cartilage and the bursa
To protect the joints, the inside of the glenoid cavity and the humeral head are covered with articular cartilage. The joint capsule continuously produces synovial fluid.
The shoulder also includes various bursae , which act as a buffer between the tissues and reduce friction.
Diseases and injuries to the shoulder
In the case of diseases and injuries to the shoulder joint, one option for precise diagnosis and treatment is shoulder arthroscopy. During this arthroscopy , the shoulder joint is thoroughly examined and can be treated surgically at the same time. The video shows the procedure for this minimally invasive procedure:
The pain caused by diseases and injuries in the shoulder area is usually not felt in the shoulder itself, but in the upper arm (especially near the deltoid insertion). Injuries to the acromioclavicular joint are an exception.
Degenerative processes(signs of wear and tear) account for the majority of all pathological changes in the shoulder. Like all joints in the human body, the shoulder can also be affected by osteoarthritis(omarthrosis). However, impingement syndrome(shoulder tightness syndrome), in which there is a constriction between the acromion and the humeral head, is also common. Other diseases in the shoulder area can include calcific shoulder and frozen shoulder.
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Clavicle fract ures are also common because they involve a very thin bone. Other injuries in the shoulder area can include rotator cuff tears (torn tendons) and shoulder dislocations (dislocations of the shoulder joint).