Joint locks manipulate wrists, elbows, knees, etc., beyond their normal range of motion in order to break or dislocate bones, injure muscles, tear tendons or rip ligaments. These grappling techniques, used in martial arts such as chin na, jujutsu, judo and Brazilianjiu-jitsu, force an opponent/attacker into a submissive, nonthreatening position.
Arm locks, such as the armbar, elbow lock, key lock, juji gatame (cross-arm lock) and shoulder lock, attempt to hyperextend, hyper-rotate or hyperflex the elbow and/or shoulder. Leg locks, such as the ankle lock, heel hook and kneebar, aim to disable the hip, knee or ankle. Small-joint manipulations twist the toes and fingers. Wrist locks rotate, supinate, pronate, hyperflex or hyperextend an opponent’s wrist. Spinal locks, including the neck crank, can opener, cattle catch, crucifix neck crank, twister and spine crank, are the most dangerous of the joint locks.
Compressions locks (also known as “muscle slicers” or “crushers”) are a subcategory for all five joint-lock types. They squeeze or squash muscles onto the bone, causing excruciating pain.