How do we use them in combat?
How we use the nerves to our advantage when in combat is we can partially immobilize or numb an opponent long enough just a split second to gain the upper hand, it is not always necessary or even always possible to knock the person out. This is due to say your skill level, experience, stress , fear , adrenaline also if the person does not feel or is able to mask the pain / sensations that is associated with the nerves being activated.
My way of thinking is to learn 20 good nerve locations that you can use without thinking it must be in your muscle memory that you can do subliminal, eg like driving. and you can produce the hit or strike with out thinking.
How do you get it in muscle memory ? Repetition repetition repetition and more repetition its the only way.
Do not just rely on knowing where the points are, please pressure test your skills, its a little bit different training with a willing partner than having a 300 pound 6ft 8 hairy man running at you with a machete in both hands.
A way I have found and tested is you strike your opponent with different energies eg If I strike GB-31 from back to front and in and up with a shin kick, in a split second or even sooner I punch CO-17 with a in and down motion then with the other hand I punch with a hook at TW-17 from back to front, you have a very dangerous / lethal combination. Out of responsibility I am not going to say anymore than that any one who studies pressure points will know what this combination will do.
Another aspect is how you put the energy into the opponent for example if you strike your opponent at Lung-6 in and towards you the opponent will jump towards you and the energy will go out along his arm towards his hand. If you reverse that by hitting the same point away from you and towards your opponent the energy will crumple him and buckle his legs.
All these points represents vital spots in the body. Every country has its own brand name for pressure points. In India we call this us pressure points as varmam points, we call this art as varmakalai, varmaadi, marmakalai, marmaadi. In other regions they called this art as dimmark or kyushojitsu and etc…