Knife Hand Blocks and the Carotid Sinus

 Among many things that martial artists have named badly is the knife hand block. 

If you try to block something with that front hand, well, good luck with that.  There is a block involved, but the larger, more obvious motion of the front hand really only works as a strike.

There are a lot of style differences in knife hand blocks, so depending on what exactly you study, the specifics are going to be a little different.  But in general, the BACK hand is the block (or trap or grab) and the front hand is a strike.  And while there is a lot to explore in that back hand, this article is about the striking hand.

There are a few interesting points to notice.

1.  Your weight is on the back leg.

Knife hand blocks are almost always done in a back stance, with the weight predominantly on the back leg.  This is to facilitate what is going on with the back hand.  Many applications involve pulling the enemy forward into the strike , so that back-foot weight distribution helps.  But the downside is that the strike has to be effective without putting a lot of weight into it.  One way to reliably do that is striking a vulnerable area like the neck.

You have a lot of important things in your neck, and hitting any one of them hard enough can ruin your day if not your life.  A committed strike anywhere on the neck is serious business.  

Bringing that oh-so-famous Martial Journeys wisdom.

2.  The carotid sinus is a prime target for the strike part of this technique.

Your carotid arteries are the main way that blood gets into your brain.  At the base of each carotid artery you have a squishy spot called the carotid sinus.  They have a lot of baroreceptors, which have the job of monitoring blood pressure in the artery so your brain can make sure it's getting the right amount of blood.  Too much blood pressure in your brain or too little is very bad, but fortunately your body is pretty good at getting it just right.

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While it's certainly not the only potential target for damage in the neck, the carotid sinus is certainly an interesting one.  I should digress for a moment to point out that it may or may not be a viable target, depending on what exactly the back hand is doing and even just the chaos of combat, the enemy's neck could be rotated any number of ways.  You might not have a good angle on the carotid sinus.  Maybe you'll  hit the wind pipe or vertebrae.  That is not any less serious, but again, that's beyond the scope of this article.

I'm focusing on the carotid sinus for this article because there seems to be a perception (which I'm sorry to say I may have contributed to) that short of a blood choke technique, an attack to this area will be painful but have limited effect otherwise.  Actually it can be much worse.

3.  This technique can end a fight.

The idea of striking a pressure point and having the person just keel over sounds like some weapons-grade bull.  And when something sounds like bull, it's usually bull.  Lean into your black belt level eye roll technique and then go hit something to try to blot said bull out of your brain.  But it turns out that some interesting and awful things can happen from a strike to the carotid sinus.

I know my audience, and you are not fans of bull.
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If you really want to understand it, I recommend this article by Brian Sagi, which explains how a strike to the carotid sinus can cause the brain to freak out about changes in blood pressure (I mean, you did squish it pretty good with that strike, and that will definitely affect the pressure, so your baroreceptors are kind of right?) and respond by rapidly decreasing blood pressure in the brain until the person falls unconscious.  Lights out, from a strike to the neck.

I would hope this would go without saying, but THIS IS NOT SAFE TO PRACTICE.  Although getting hit with this is usually not lethal.  Usually.

If you really, really want to practice disrupting a friend's brain function and evacuating blood out of their brain, I have the following recommendations.

1.  Don't.

2.  Watch this video before trying it out.

3.  Seriously, don't play games with this stuff.  

You can safely practice a knife hand block by striking air, or by your partner keeping a hand up in front of the neck.  Hit the hand or arm instead.