Re: What's in a yonkyo?
The way I was taught yonkyo was to press the base of the forefinger into the sensitive area.
In other words, the forefinger and several others, are arched back while the pad on the palm just below the finger itself is pressed into the nerve, while the sword extension type forward motion is executed. I agree with the others that it as with all aikido holds will only work with all the balance, leading ki, etc, no forcing bringing you into the hold. Once uke has his balance again, well we know about that.