Knee Issues. Please help me find a website that shows the muscle anatomy of the knee?

I am looking for a website that shows, in good or great detail, the muscle anatomy of the knee (3d and interactive hopefully) as well as a better explaination about the stabilizing muscles in the knee for the knee cap. I cannot afford to purchase any software so right now I need a website that shows it for free. I am already familiar with the insides (ligaments) of the knee I just need to find a visual model of the muscles now so that I will understand what muscles I need to concentrate on when exercising to help stabilize the knee cap . Can anyone help?