If you want to learn anatomy without learning to draw, I would suggest making your next major project a full-body anatomical model. This lets you really just focus on learning the anatomy itself, without being distracted by any artistic urges or "stylization".
Start with the bones, use an anatomy book for reference, and sculpt them all up. Import reference images images into zbrush as needed and work hard until they all are right. From there, add your muscles one by one and learn how they connect to the bones. It should probably take you between two weeks and a month if you set aside a couple hours a day to work on it.
When you're done, switch to the other gender, and do another one! You'll find you can re-use a lot of your work by deforming the model, but you'll need to re-do some things completely (especially in the hip area). This one will go way faster.
If you still want to learn more, move on to something like a bodybuilder, a child, or a horse, or something else new, and do the whole thing again.
It will be tedious, time consuming, and difficult to stick with, but this is the best way to really learn what's going on.
For reference materials:
- "Artistic Anatomy" by Sarah Simblet. It has great drawings and photography, and is focused on those parts of anatomy that matter for a visual artist. http://amzn.com/078948045X
- "Anatomy for the Artist" by Paul Richer. A much more technical study of anatomy, focusing on the detailed interaction of bones and muscles. http://amzn.com/0823002977
- For technique in Zbrush, this short video by Ryan Kingslien shows you how to quickly create muscles using CurveTubes. You can probably see how a similar technique would work well for roughing in long bones. http://www.isculptstuff.com/2012/08/...our-model.html
- "Sculpting Realistic Game Characters" by Ryan Kingslien is a good one for later. It's better if you already have the basics down, and helps you organize your knowledge and internalize it. http://amzn.com/047087256X
So yeah. That's my advice.