An armbar being used by a Brazilian Jiu-Jitsu practitioner.
An armbar (called jūji-gatame in Japanese) is one of the most common joint locks, intended to hyperextend the elbow joint. The most commonly known version involves squeezing the opponents leg between the thighs and pushing upwards with the hips; however, the armbar can be applied in a number of ways, such as holding the wrist and pulling upwards with the elbow in the armpit.