Medical Brain controlling cells individually?

[CAllFlow]

So, this is my first post in the medical science section of the forum. So I was just in the shower and a question occurred to me. When I hear about how the brain controlling the body it's always "the brain tells this group of muscles to do something"...or 'the brains tells this organ system what to do". I was wondering does the brain "speak" to individual cells or collectively to a large group of cells in the same system. Like, when I move my arm does the brain tell my bicep to contract or relax or does it go through each and every cell in my arm and tell it exactly which direction to say contract and how much? I've done some searching through the interwebs and wasn't able to find any information relating to this topic.(And if it's because this is a very basic concept that most people should know then I'm sorry to have wasted your time.)


Any help and/or enlightenment will be greatly appreciated :) TY

 

[Lievo]

Usually, the brain doesn't need to control each motoneuron individually. Instead, the motoneurons are recruited according to the http://www.physio.unibe.ch/publikationen/report_Lagrange.pdf" .

However, it's likely possible to control individual motoneuron using an appropriate biofeedback (such as the display of the signal coming from an electrods positionned in one muscle fiber). This is just not the way we usually recruite our muscles' fibers while moving.