(dislocated shoulder) Your shoulder joint is made up of three bones: your collarbone, your shoulder blade, and your upper arm bone. The top of your upper arm bone is shaped like a ball. This ball fits into a cuplike socket in your shoulder blade. A shoulder dislocation is an injury that happens when the ball pops out of your socket. A dislocation may be partial, where the ball is only partially out of the socket. It can also be a full dislocation, where the ball is completely out of the socket. Your shoulders are the most movable joints in your body. They are also the most commonly dislocated joints. The most common causes of shoulder dislocations are Sports injuries; Accidents, including traffic accidents; Falling on your shoulder or outstretched arm; Seizures and electric shocks, which can cause muscle contractions that pull the arm out of place. A dislocated shoulder can happen to anyone, but they are more common in young men, who are more often involved in sports and other physical activities. Older adults, especially women, are also at higher risk because they are more likely to fall.

A dislocation of the shoulder joint.

A displacement or misalignment of the humerus with respect to the other bones of the should joint. Note that a subluxation is a partial dislocation.

Displacement of the HUMERUS from the SCAPULA.

In shoulder (glenohumeral) dislocations, the humeral head separates from the glenoid fossa; displacement is usually anterior. Shoulder dislocations account for about half of major joint dislocations.

Shoulder dislocations may occur from a traumatic injury or from loose capsular ligaments. Different conditions may affect the stabilizing structures of the shoulder and, thus, negatively affect patients with shoulder dislocations.

A dislocated shoulder is an injury in which your upper arm bone pops out of the cup-shaped socket that's part of your shoulder blade. The shoulder is the body's most mobile joint, which makes it susceptible to dislocation.