This joint complex includes three bones the humerus (ball portion of arm bone), scapula (shoulder blade), and the clavicle (collarbone).
There are two main joints in the shoulder the glenohumeral joint (ball and socket) between the humerus and scapula, and the acromioclavicular joint (AC joint) between the collarbone and scapula. The shoulder complex allows for significant motion and is loosely stabilized by capsule and ligaments.
The main stability of the ball and socket joint of the shoulder is provided by the four rotator cuff muscles and the biceps tendon attachment. A labrum (cartilage structure) provides a cushion and acts to increase stability of the glenohumeral joint.
Adhesive capsulitis ("frozen shoulder") - inflammatory condition involving the soft tissue surrounding the ball and socket shoulder joint. Trauma, prolonged immobilization, overuse, or surgery can lead to this condition.
Biceps tendonitis ??“ inflammation or degeneration of the biceps tendon at the upper part of the arm bone (humerus) can result from overuse injury, or trauma. The biceps tendon attaches to the upper socket of the ball and socket (glenohumeral joint) to stabilize the shoulder joint.
Acromioclavicular joint (AC joint) separation ("shoulder separation") - acute injury of the soft tissue stabilizing the joint at the end of the collarbone (clavicle) and top of the shoulder blade (acromion).
Acromioclavicular joint (AC joint) arthritis ??“ this is a degenerative condition involving the joint at the end of the collarbone (clavicle), and top of the shoulder blade (acromion). Most commonly seen in laborers, weight-lifters, increasing age, and can be associated with rotator cuff tears, or impingement syndromes.
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Jul 15, 2010