I think the drawing looks really nice! The leg feels solid and there is a nice back n forth rhythm; outside thigh, inside knee, outside lower leg, inside foot. - You migh benefit from getting into a mannequinization mindset; doing the same when drawing the anatomical details as when you draw the major forms of the figure, with the difference being that the mannequin you're building for you're anatomy studies is much more complex. It might help to think of everything as boxy forms, to get clear and defined plane breaks. - Before adding in tone, I think it will help to first indicate the border between light and shadow, to get a clear design. Hope this helps :)