>>127277
I am unaware of any specific nerve that can knock a person unconscious. Perhaps you could begin by studying pressure points on the human body.
http://www.pharmaresearchlibrary.com/wp-content/uploads/2013/03/A-Textbook-of-Clinical-Pharmacology-and-Therapeutics-5th-edition.pdf
There is a complete description of the pain pathway on page 155 in the above textbook.
https://www.drugabuse.gov/publications/teaching-packets/neurobiology-drug-addiction/section-i-introduction-to-brain/4-pathway-sensation-pain-reaction-t
In this second link, you will find a more basic and general description of how pain is translated from a physical sensation to a mental understanding of pain - aka how you know to say "Ouch!" when you burn your fingers on a hot stove.
Using the aforementioned information, I will now attempt to briefly answer your question. There are two main components in understanding the response. The first is understanding the nervous system and the pain response. The second is understanding how the specific act of 'focusing' can cause an effect in another. As far as the nervous system goes, you must know that the perception of pain is not in the body, it is in the mind. The nerves simply relay the presence of harmful stimuli to your brain. Therefore, it is in my opinion equally effective to focus upon the mind of another, rather than just their nerves. However, the nerves may be more sensitive and more easily agitated depending on the person you are dealing with. Like many things, the proper point of focus must be determined by the practitioner in the moment.
And the question of focus is a difficult one, but I will try to answer as best as I can. Focus is something that the entirety of the magickal, mental, spiritual, whatever you may want to call it journey depends upon. Extraordinary amounts of time should be spent developing focus in and of itself before beginning to try and apply it to the real world. I know this isn't the most pleasing answer, and it seems like a non-answer. That's because it kind of is. But imagine a world in which the focus of an average person could easily be activated towards knocking another unconscious or causing another pain. It would be quite the hectic world wouldn't it.
So, the actual question of HOW FOCUSING on a NERVE could cause PAIN can now be answered. The last piece of this puzzle lies in the HOW part of the question. And this is simple, and in fact you probably already know it. The universe is mental, and you seek to alter that reality. But before altering the reality of others, you must learn to alter your own reality first. I would contend that only in the rarest cases will an individual be able to mentally produce an effect in the world without first producing it within his own body.
I hope this was helpful.