Twitching...triggers?

Hi everyone
I’ve had muscle twitches/fasiculations for ages but just recently I’ve found a couple of them can be intentionally triggered (eg squeezing my eye shut briefly can set off my eyelid twitch, opening my hand flat can set off a twitch on the side of my palm), this is new to me as previously they’d all been random and taken me by surprise, mostly they still do but I was curious if anyone experiences any that seem to have a mechanical trigger for want of a better word, and even more curious if anyone knows what causes it, like is one type of twitch more associated wirh peripheral nerves and one more central, or is one a problem with the muscle itself rather thsn a neurology issue etc. Don’t spose anyone knows?

Thank you for any experiences or info!