The lines are stylistic, and just as in the rest of the piece they are not impacted by lighting.
Addressing the direction of the lighting, it is above, to her right, and slightly in front, but not much.
I made a 3d rendering of my lighting setup with a crudely modeled wrench. I get the same shadow and highlight pattern. I guess I am not understanding the issue with the lighting?
I know it may sound like I am being defensive, but I promise I am not. I am just trying to understand what you guys are seeing.