I've been making some new anatomy drawings in my Moleskine. A fantastic tool for creating a figure pose is DAZ 3D. I use the Michael character model with the muscle textures and morphs. It's a brilliant way to get a good photo reference. The body morphs are excellent as well. You can make your figure super muscular, skinny, obese, whatever you need. Then just set up your lights and render an image.
I made two versions of each; an ink and copic marker drawing, and a colored pencil muscle map drawing. Then I scanned the images into Photoshop, aligned them together, and set the muscle map as the top layer at Multiply with 50% opacity.