This is known as the origin. And this side where the origin is located is known as our proximal end while the other end is known as our distal end. And this location is known as our insertion. So the point where the muscle attaches to our movable bone via the tendon, that is known as our insertion. So the radius and the ulna are the movable bones. Our humerus is the immovable bone and this is our proximal end.