I agree with Kimchan; the fitting of the joints does look a bit inaccurate, but otherwise, it's good to see someone that cares about anatomy!
Kart, I would suggest doing like Franz and drawing your own hand from life in different positions and perspectives for more practice. That helped me a lot. A combination of understanding proportion and anatomy (especially muscular), and drawing from life is probably the best way to learn the human figure. Drawing nudes all the time at art school helped me especially.
If anyone is looking for a really good anatomy book for artists, there's one called Visualizing Muscles, by John Cody, M.D. It has a couple hundred photos of a male model with muscles drawn right on him. There are tons of different poses, so that you can see how movement affects the appearance of each muscle.