"Figure Drawing - Design and Invention" by Michael Hampton is a MUST HAVE anatomy book to add to your art book collection. It costs $35 and is 235 pages of awesome! He breaks a lot of concepts and aspects of the body into different chapters which makes things so much easier to understand. It's insane.
Check out his website, he constantly updates his followers with more anatomy studies here: Figure Drawing
NOTE: These sketches are purely for my own learning.
These studies are based off Michael Hampton's book and are not mine.