The term rear naked choke likely originated from the technique in Jiujitsu and Judo known as the "Hadaka Jime," or "Naked Strangle." The word "naked" in this context suggests that, unlike other strangulation techniques found in Jiujitsu/Judo, this hold does not require the use of a keikogi ("gi") or training uniform.

The choke has two variations: in one version, the attacker's arm encircles the opponent's neck and then grabs his own biceps on the other arm (see below for details); in the second version, the attacker clasps his hands together instead after encircling the opponent's neck.

"Figure Four" variation
In martial arts, the term RNC often refers to the hand-on-biceps version (sometimes the shoulder since hands on shoulder allows less space for the other person to escape but getting in that position is rare.) This variant is considered to be a "blood choke" because it restricts blood flow to the brain via the carotid arteries. When done correctly, it can cause temporary unconsciousness in a few seconds. The following is a description of this technique using the left arm -- the attacker's left arm encircles the opponent's neck, with the opponent's trachea at the crook of the elbow. The attacker's left hand then grasps his own upper right arm (biceps region). The right hand is placed behind (or occasionally on top of) the opponent's head. The elbows are then brought together such that lateral pressure is applied to the neck on both sides.

This technique is often used in certain grappling martial arts such as Brazilian Jiu-Jitsu, and is one of the most common ways to win a match in mixed martial arts competition. It is also a lateral vascular neck restraint used by law enforcement. It is known in Brazilian Jiu-Jitsu as mata lećo, meaning "kill the lion" or "lion killer" in Portuguese, likely as a homage to the tale of the slaying of the Nemean Lion by Heracles (Hercules) using a chokehold (various paintings, however, depict Heracles as using a frontal chokehold instead).

"Clasping Hands" variation
This variation has the supporting hand clasp the hand of the choking arm, allowing more pressure to be applied to the neck, but losing some of the control of the head. This alters the choke somewhat so that it is more likely to be applied as an airway-restricting choke or mixed blood and air choke, which results in more pain but a slower choke-out. As such, this technique is less frequently used at advanced levels in Judo. Nonetheless, it has seen some successful applications in mixed martial arts competition: for instance, it was used by Fedor Emelianenko, a heavyweight champion in PRIDE, to defeat Kazuyuki Fujita at the PRIDE 26 event in 2003. Fujita tapped out about five seconds after the choke was applied. It was also used by UFC fighter Matt Hughes to defeat Frank Trigg in their second fight which was transitioned from a hand-on-biceps version of the RNC.

Click here to view a video of the Rear Naked Choke technique.

Source: Wikipedia (www.wikipedia.org)