The shoulder joint is vulnerable to dislocations from sudden jerks of the arm, especially in children before strong muscles have developed. Dislocation of the shoulder is extremely painful and may require surgical repair or even cause permanent damage.
The shoulder has several other important structures: The rotator cuff is a collection of muscles and tendons that surround the shoulder, giving it support and allowing a wide range of motion. The bursa is a small sac of fluid that cushions and protects the tendons of the rotator cuff.
Shoulder Joint. The most flexible joint in the entire human body, our shoulder joint is formed by the union of the humerus, the scapula (or shoulder blade), and the clavicle (or collarbone). Commonly thought of as a single joint, the shoulder is actually made up of two separate joints – the glenohumeral and acromioclavicular joints.