I am right-handed. Which means that when I hammer down a nail, I hold the nail in my left hand, with which I can hold it straight and at a controlled position.
This is true in situations where the task of holding something in place is simultaneous with a more complex task, such has hammering, done with the right hand. But I note that even when there is no other task, I personally use my left hand to hold in place, e.g., a bottle that I am filling up in a stream of water.
To generalize a little, it seems to me that while I use my right hand for precise motion or applying a force, I'll use my left hand to maintain a position against forces.
Is this behaviour something documented? Does one develop specific brain control to implement this controlled-position tasks?