Anatomy.

Here are a few useful anatomical diagrams for you reference.
Starting with the skeleton!

 I find the early anatomical waxes fascinating, not least because they are Sculptures not casts or plastinations!

Link to anatomical waxes

There are now countless Anatomical Atlases on the web..Link

I am trying to procure a flayed figure such as this..

Traditional flayed figure sculpture as used by Royal academy students

There are many many books on the subject of Anatomy for artists.

Alec Tiranti stock many! 

Tiranti is the one stop shop for all sculpture Materials Tools and Books.