This work is better suited to a pencil. There isn't much in the way of the pixel to critique...
You'll learn anatomy by feeling the shapes as you make them, by familiarizing yourself with the human body with SCIENCE and with practice... Not by using a line tool. There's a level of disconnection there that is too great to really benefit you. Line art like this is very 2d, and there are no two dimensional people. You would be best off using a less opaque and more dynamic media. Generally this means pencil, paint, chalk, just something more practical, fast, and fluid.
Pixel art is about paying attention to the individual pixels. Just because you used a single pencil tool or didn't use automatic AA does not mean this is pixel art. You can argue that clean lines are pixel art, and they are, the refinement of an outline very much fits the definition, but overall the intent of this work is not to produce art but to study anatomy.
You might want to take this here:
http://www.wayofthepixel.net/pixelation/index.php?topic=6528.0Edit: asdf beaten to the punch again
