M.C. Escher is a great artist to study, I have learned so much from doing these. He holds the secret to a lot of work relating to perception and the use of concave and convex forms in composition. I did cheat a little bit when I made this. I used poser 7 anatomy models so make a composite of the muscle tissue layer, and the skeleton. Then I did a rough digital sketch and used a graphite transfer technique to get it into my sketch book. There is method in the madness.