The knee was fascinating as well. I learned a lot but the thing that stuck out most to me was the fatty pellet. This seems to be the thing that confuses most young artists because it varies so much in people that if you don't understand the anatomy underneath it you don't have much of a chance of figuring it out. It sits onderneath the patella and keeps the joints from causing sparks by rubbing together so much. Another thing that fascinated me was how the bones were designed so well as to be able to hold all of weight and still be used to help us move about. Well, I drew it from all four sides. Enjoy!!