Is it even remotely possible to do this to a full grown man in reasonable shape, or is this a martial arts fantasy?
Not the way you see it done in the movies… where the guy puts his two palms on the victim’s ears and quickly turns his head to one direction so the victim is looking to the left/right. That version doesn’t even make sense. You can’t break something by bending/turning it in the direction it was made to turn.
I think the first thing anyone will do when you grab thir head is to tense up their neck and try to pull it either up or down to get away… while simultaneously flailing or pushing their hands into your face. That never happens in the movies.
The move can be done in real life but AFAIK it is a lot more brutish and inelegant than you ever see in the movies. I think you have to grab the head in a really good grip with both arms and give it a really hard crank in an awkward direction - usually from a dominant position like from the rear or with the guy bent over in font of you. And of course it helps to have your victim untrained, scared or unaware, and outmatched physically. Try it on pretty much anyone like they do in the movies and you’d be eating punches or thumbs in the eyes… not to mention that it wouldn’t even work sans the counter-attack.
A KO punch or choke is much easier to do on the unsuspecting types of victims you see this done to in films. If you’re a real secret service or miltary badass, use a weapon or better yet just have one of your riflemen shoot the guy from a distance. Martial arts fantasy I say.
I have a friend who buys into the myth of martial arts and he swears that some twelve-millionth degree blackbelt showed him the “real” way to do this.
He says you need to extend your arms out, crossing them, and land your left palm on your opponent’s left shoulder. Land your right palm on your opponent’s lower left jaw, and extend/push really fast.
Looks like it would hurt pretty bad but death? I’m skeptical.
My old judo instructor taught a street takedown that involved grabbing the hair on the back of the heand with one hand and putting the other hand on the chin and then twisting the head like they do in the movies to rotate the person as you bring him down.
The neck-breaking techniques I’ve learned all involve creating a lot of pressure with the whole body to generate the necessary force. Here’s an example of the sort of thing I’m talking about, where a broken neck may be possible: http://www.combatwrestling.com/neckcrank.jpg
In the movie scenario, I think the body would just turn along with the head. Might get some good whiplash mabye?
Jenny Calendar Is Still Alive!!
Last reported living in Bulgaria and struggling with soft tissue damage.
(Sorry, I couldn’t resist. For those not in the know, Jenny Calendar was a popular ‘Buffy the vampire slayer’ character suddenly killed off of the show in the second season, dead of a variant on this attack.)
I was taught a neck snapping move in Tae Kwon Do that involved placing one hand on top of the head, another under the chin and then cranking the head in such a manner that it ends up sort of sideways on the shoulders.
I’ve never gotten the chance to test it for real so I don’t know how effective or easy it would be to execute in an actual fight.
This is in one of the katas, koshiki-no-kata if I recall correctly. The English translation of the name is “neck plates twisting”. Supposedly it is an old jujutsu technique against an armored opponent. Might work as a take-down, but I am skeptical it would work to break the neck. You would have to be awfully strong to generate enough force to break the neck by twisting that way. Dislocate the jaw, maybe, pull out a lot of hair, perhaps. Break the neck? I doubt it.
If you are strong enough, maybe. Another possible way is a front headlock and then a back sacrifice throw, done very fast and very hard. Or possibly a face-plant tawara-gaeshi, or ura-nage where he landed on his head.
Regards,
Shodan
Um, I guess I stated that poorly. It was a takedown, not a way to kill somebody, so it was an example of an expert contradicting what the movies show.
Unfortunately I couldn’t find a good example of a neck-crank. The photo does illustrate the sort of real power that will be required to break a neck, which I think is the issue.
Hopefully I’ve cleared up my poorly constructed remarks. 
Once a month, my Chiropractor snaps my neck - cracks it - first one way (say to my right), and then the other. It’s a smooth, small move, unlike the olden days of Chiropractic.
I.e., when I was a kid. We had a Chirpractor as the resident medico at Boys Club Camp, and for some reason, he cracked my neck (both ways), but it was more violent than what my present Chiro does. If I remember correctly, the Camp guy put one hand on the back of my head and one holding my chin. He then rotated my head back and forth, back and forth until i was sufficiently relaxed then, he wrenched my head to the extreme left and SNAP!!!
He repeated the procedure for a right SNAP!!
Never went back to this guy for any complaint. It just didn’t seem right . Years later I heard (for what it’s worth) that bad shit can happen with this procedure - spinal cord damage, prehaps?
With this boring explanation, what I’m trying to say is you can probably inflict serious damage with a head twist, but your victim probably has to be stupidly cooperative, or exceptionally weak, or very drunk.
Like js_africanus, a kickboxing instructor once taught me a takedown move involving moving your opponent’s head down and in a twisting motion, but the aim of this takedown was to get the guy on the ground so that you could immobilize him or get away from him, not kill him. The theory being that where the head went, the body would follow.
I think that breaking someone’s neck ninja-style would take a good deal of force and power. It wouldn’t be a simple head twist a la hollywood.
We were taught it when I studied Tang Su Do back in the 80’s in Korea. IIRC, you grabbed the face with one hand, the back of the head with the other and twisted it around sharply. Of course, all this was preceeded by breacking the othe person’s elbow, yanking their wrist up between the shoulder blades and then dropping them straight down onto the broken elbow, so one might assume they weren’t fighting back as well as otherwise.
I had someone try it on me one night - a drunk Korean guy who was apparently offended that my Korean g/f preferred me to him. He caught me totally by surprise (some ninja I am) and dropped me to the ground, then grabbed my head with both hands. I was, naturally frightened and punched him in the nuts as hard as I could - he let go. Shortly afterward several of his friends came running out of a bar and dragged him away. In retrospect, I’m quite glad they did. My neck was pretty sore the next few days, but the elbow I’d landed on hurt worse.
So, yes, it can be done, but it does take some strength.
Speaking of neck cranks, here is Mark Kerr putting one on Igor Borisov 4 years ago in Japan.
Igor was hurt pretty bad - bad enough to be carried from the ring on a stretcher. I don’t think he’s fought professionally since then either, although I don’t think his neck was broken. If he hadn’t tapped out he could have got hurt even worse…
But keep in mind it took a very good 250-lb (allegedly roided) wrestler a good 30 seconds to get the hold on and pull it hard enough. Like I said, the quick effortless standing “twist-neck-snap” is a hollywood myth.