Toe bone connected to the foot bone. And the foot bone is connected ...

Not bones, nerves.

So I had this itch at the very top of my head. I scratched it. It was one of those “large” pieces of dander up there that needed removal. So I did.

But as I scratched it loose and away, the roof of my mouth had the exact same itch.

Coincidence or am I weirdly wired?

Head nerves be weird. Take the case of the tooth-ache on the wrong side of your jaw.
I have no cites but my own. Happened to me twice.

Several decades ago I designed a bunch of a equipment for a neurologist who was trying to figure a lot of this stuff out. There’s some definite weirdness in our nervous system.

For one thing, there’s a bit of “crosstalk” (to use an electrical engineering term) between nerves. One common symptom of this is that your ear can hurt when you really have a problem with one of your teeth and not with your ear. The nerves for your jaw happen to join into the same nerve bundle as the nerves from your ear.

I haven’t looked at a chart of exactly where the nerves of your scalp are routed, but from the OP’s description I’m guessing that they end up in the same nerve bundle as the nerves from the roof of the mouth.

Your temperature sensing nerves are also fairly decent at detecting changes in temperature, but truly suck at detecting absolute temperature.

And there is also a weird thing with nerves where neurons tend to be a bit reluctant to fire at first, and then once they start firing, they get reluctant to stop. The end result is this weird integration (calculus type integration) thing. If you have a machine that can precisely control the temperature of a very small area of your skin (one of the things I made), and you vary the temperature for 1 second at 40 deg C, then 2 seconds at 20 deg C, then 1 second at 40 deg C, then back to 2 seconds at 20 deg C, and keep repeating this, your nerves fire as if the temperature is going 40, 20, 41, 21, 42, 22, 43, 23, etc. In other words, the nerves keep adding on to the stimulus that your brain receives based on previous stimuli. I suppose the point of that is to help stop you from getting burned, but it’s interesting that all of this happens down in the nerve fibers and not in the brain.

I get this occasionally. For me though I’ll scratch a spot on my back/ribs and it tweaks something in my thigh. It works in reveres too, thigh to back.

Weird.

A number of years ago I had some major dental surgery. The oral surgeon had to harvest some bone from my sinus for an implant. I was awake during the procedure, but could feel every single thing he was doing, without the pain… on the opposite side of my mouth. I knew he was working on the left side, but I felt it on the right.

And then there is foot reflexology. My ex was taking a course in it, and one night he was practicing on me. I was having a lower back spasm, but hadn’t told him. Everything was fine, as he applied pressure to various spots on my soles, until suddenly he pressed one spot, and I yelled “YOW!!!” He replied, “Lower back problems tonight?”