Probably my thoughts deceiving me as usual. Though the blunt part of the knife hurt a bit and caused quite a loud sound, but it felt almost like the equivalent force of your hand knuckle bones knocking on your head, kind of the same sound occurs with both, just a bit more noisy with the knife probably due to the material and the fact that it's not covered in skin like the bones are. Regarding the pointy edge it caused quite an itchy feeling after, like as if my skin got pressed down and a small dot mark appears. But my guess is that the skin covering the skull is a bit more tough than that of ordinary skin? Maybe a bit like leather similar to that of the skin on the elbows?

EDIT:
When you mention: "concentrated energy" do you refer to the event of such a hard focused blow temporarily changing the shape of skull or fracturing it? I mean how's it possible that a hard blow to a small area can cause sub concussive impact if there is no movement of the head itself? If that's what you meant. Can the skull move even though the head doesn't when the energy is concentrated to a small area?

Concentrated energy means all of the force is concentrated on the small surface area of the tip of the blade. That concentrated force is why you felt the contact. If the tip of the blade had a larger size, you would hardly notice the contact.

This was not a sub-concussive impact.

How is you search for help with your anxieties going ?

Scratching the back of your head with a sharp pointed knife?

No you're getting the wrong idea of it. Well yeah I was kinda scratching the back of my head, but not with the knife on purpose. It just kinda stabbed my head quickly, that's it. Wasn't meant to touch my head with it, just one of those times where stuff happens and you realize you never should've wielded a knife while touching your head with the same hand, sounds obvious, but really didn't think about it at the time.

Haha enough explanation. A last question, is concentrated force more likely or less likely to cause a concussion? If it was spread across the skull instead of a small area, would the odds of concussion be higher or lower? Or is concentrated energy what causes local concussion injury in one area of the brain and spread energy causes, well, spread brain injury? Or does that have no relation at all?

Since there was no acceleration or deceleration of the head I can be sure no concussive injury happened? Or is there other factors to consider? Cause I've never been told that any other phenomenon can produce it.

The 'concentrated' force has nothing to do with concussion. I was only mentioning it regarding the pain you felt to that small area of your skin.

The rest of your questions do not even make sense regarding this knife issue.

It is apparent you either don't understand the basic concepts of force/physics or don't want to accept the basic concepts of force/physics because they conflict with your anxieties.

There is no point in further discussion regarding these concepts. Your issue is not about forces against your head. The issue you need to resolve is the anxiety you have and how it causes your mind to twist and distort information to try to make it support you anxieties.

You need to find help with your anxieties. No amount of discussion of the forces will resolve your anxieties.

I'm doing everything I can to subdue my anxieties, and it's slowly working, but this is one of those times where it's an occasional setback.

If say, I did fracture my skull from doing it, it would hurt like hell right? I would get a terrible headache even though it's only a tiny hole due to the pointy edge of the knife. I mean, my nails almost hurt equally much if pressing on the head. But if it hypothetically did penetrate the skull in any way, even by a tiny bit, signs and symptoms would always occur right? No longer scared of the blunt part of the knife impacting the head, now it's more if it could've. stabbed through the skull creating a small hole I wouldn't notice or feel.

EDIT:
It sounds like I stabbed myself in my head with a sharp focused blow, but its nothing like that. More like the force of dropping the knife from a low altitude impacting with the tip of the knife.

Yes.

Yes.

The main sign of having stabbed oneself in the back of the head with a knife would be bleeding... lots and lots of bleeding.

If you penetrate your skull with a sharp instrument, your major worry would be infection, IMO.

example:
http://columbianeuroicu.org/diseases/infections.html

Yes. I recently slipped and fell backwards and slammed the back of my skull into the edge tile of an outside unsealed terracotta step (known for holding moisture and moss). The amount of blood loss was grossly scary for such a smallish wound. The thing I was most concerned about the actual wound itself after they cleaned it out and stitched it up was infection because some of the debris was still imbedded in the skin around the wound.

btw Minimac, you would need to penetrate the skin before you got to the skull.

Yeah but what if it penetrated the skin without me knowing? Would it still cause lots of bleeding by such a small wound? I mean the skin covering your skull feels fairly thin, only the forehead seems to have a thicker layer of skin covering. Please don't judge now, but I tried with the same strength on the forehead with the somewhat sharp object, it didn't penetrate the skin on the forehead, don't even think it left a noticeable mark indicating any kind of impact. But just worried that the skin is much thinner at the back of the head or top of it.