Quote - I was thinking with displacement map you could detail muscles tendons etc etc as detailed as any mesh.
normal map ,same as displacement map just lower polycount.

 

Yes, that's true. But tendons flex and distort when a body moves, causing shadows and contours that aren't present in a relaxed state. Displacement maps don't represent this change due to their "always on" static state. So I use them to represent skin pores and wrinkles and things like that, that don't change a whole lot when the muscle beneath the skin changes. Geometry takes up less resources than maps these days, so its actually better to have a higher res mesh and use maps to enhance the geometry, instead of being a substitute for it. But for game characters, and models that require a lower poly count, displacement is a perfectly valid alternative.

 

~Shane