Three.js rotating a group around one children's center

I am a newbie in 3D technologies, and I have to draw a hand model. I use just regular spheres and cylinders for that. But, when it's time to move fingers I have some troubles with point of rotation.

For instance, I have 2 spheres and one cylinder. I bind them into one Object3D and then I perform rotation, but it rotates very strange to me. How can I setup this object to rotate around 1st sphere center. Thanks.