How to keep a bone in place when posing/animating

I’m new to animating in Blender and trying to figure out how to keep a bone in place (pin?) while posing for animation. My character is a monkey swinging vertically across a ledge of a wall. I want to keep the hand completely still, in place, while rotating the rest of the body from the arm. But every time I try, the hand moves along with the rest of the body. Is there some way to pin the hand in place during animation? Thanks in advance!