One of the most recommended books on anatomy is
Bridgman's Complete Guide to Drawing from Life
. While admittedly a great book, it can be a bit hard to follow. From Bridgman's chaotic, yet beautiful linear drawings, (made all the more difficult to follow by poor reproduction) to the somewhat erratic presentation of the text (due to the book being little more than a cobbling together of notes from his students) it can be very intimidating to the novice artist. The way I was taught to study Bridgman by Jeff Watts was a three tier process.
First: Read and understand the text as best you can (I like to have
Human Anatomy for Artists: The Elements of Form
close at hand to shed light on anything that is not clear)

Second: Translate and copy Bridgman's drawings into a tonal representation (this forces you to understand what you are drawing rather than just copy his marks)

Third: Find photo reference similar to Bridgmans drawings, and draw from them while trying to identify the shapes you learned from Bridgman. (I was taught to use female bodybuilders, or natural atheletes. So the muscles are clearly defined, without being overblown light steroid enhanced men)