Vital areas along the arms and legs are easy to reach and damage from strikes is usually minor. Wrist and elbow locks are the most common targets, since most attackers try to grab you or strike you with their hands. However, be careful when applying joint-locks. Only apply the amount of force needed to neutralize the attack since joint-locks can be very damaging. The use of excessive force, even in self-defense, is illegal! If you are forced to dislocate a joint, never reset it on the scene. Nerve fibers and/or blood vessels could be pinched or severed. This type of first aid should only be performed by medical personnel under controlled conditions.
Shoulders, as well as hips, are ball-and-socket joints that have large range of movement but they may be injured if over extended. The shoulders are highly susceptible to separations. Shoulder dislocations occur more frequently than in any other joint of the body. Even in the well-conditioned body, only a small amount of force is necessary to dislocate the shoulder.
Elbows, as well as the knees, are hinge joints that move primarily in only one direction. They are more susceptible to locking by hyperextension and twisting techniques than are the wrists. If you apply enough force against their direction of movement, it will cause extreme pain or possible separation of the joint.