A shoulder dislocation occurs when the head of the humerus
(upper arm bone) pops out of the shallow shoulder socket of the
scapula (called the glenoid). This can happen when a strong
force pulls the shoulder upward or outward, or from an extreme
external rotation of the humerus. Glenohumeral dislocations are
generally classified by the direction of dislocation of the
humerus. Dislocation can be full or partial: - Partial
dislocation (also called subluxation)—the head of the humerus
slips out of the socket momentarily and then snaps back into
place - Full dislocation—the head of the humerus comes
completely out of the socket Shoulder dislocations can also be
associated with fractures—one can have a fracture and
dislocation at the same time. Nerves and blood vessels can
sometimes be injured with a severe shoulder dislocation,
requiring immediate medical attention. Shoulder dislocation can
be caused by: - Falling on an outstretched arm - A direct blow
to the shoulder area, such as in automobile accident - Forcef