what part in suspension controls high speed shimmy

What is your question?

I already know I need struts, but exactly what parts would cause my volvo to shimmy (bounce) at high speeds? If I am going around a corner, my car will jump all over the place. I was told that it was my ball joints. (looking for another opinion). I was thinking it was my wheel bearings. If you have some experience in that area, plus weigh in with you opinion. Thank You!!!!!!