Pinching the trapezius isn't going to knock anyone out. It's not physiologically reliable. Most knockouts occur due to an impact on the brain (striking the head, often the chin or back of the head) or a change in blood pressure (a choke or strike to the side of the neck can drop blood pressure). Pinching a muscle does neither. It can hurt like the dickens, but that's about it. Maybe someone really frail and sensitive to pain might have a bad reaction, but nobody even reasonably healthy will.

Edit: I'm unable to find any article on Scottish gangs knocking people out with a punch to the neck.

Yes, "pressure points" exist. Their ability to knock someone out seems to be predicated on whether or not a master is performing on a student; they seem to not work that well on random strangers. If you know so much about pressure points, why bother asking the question? I'm throwing some honest-to-goodness science your way, and you're ignoring it.

If you were truly the ultimate Trekkie, as you claim to be, then you would know the Vulcan Neck Pinch was a fabrication - and even if it wasn't, then, as callsignfuzzy pointed out, you'd already know exactly how to do it, and would hardly need to be asking us (no, Mitt Romney and Scottish gangs are not using it - and seeing as how I happen to work for Mr. Romney, I think I'd know if he ever had to defend himself physically, against a rapper or anyone else).

Leonard Nimoy actually invented the Vulcan Neck Pinch after a script for an episode of the original Star Trek series called on his character of Spock to knock Captain Kirk unconcious by striking him on the head with a hand phaser during a fight, and Nimoy felt that that particular method was too violent given the Vulcans' non-violent viewpoints (as well as Spock's established personality specifically). It doesn't actually work in Real Life, and Nimoy never claimed it (or anything specific that he might have based it on) did.

No its not, not from that prospective. The vulcan nerve pinch was fabricated, for a tv show.

edit:> from kyoshu its not one point that knocks a person out its multiple points at specific angles and combinations.

Here's some help: