This is the refinement stage where the joints are joined together to become one cohesive mesh by "dynameshing" in Zbrush. Certain parts that can be hidden through seams will remain in its own subtool. A little bit of resculpting is needed at these joint areas to correct anatomy errors. The wrist is a prime area to fix because of how the radius and ulna work together as we rotate our hand. Initially during the T-pose the body is sculpted with the palms facing a certain direction, so when we pose our character the bones will have to change with it. The musculature changes as well as the skeletal structure, muscles bulge or flatten depending on how we contract our limbs. Muscles also squish as shown on the right calve muscle, however its always tricky to try and maintain the same volume as you show the squish or relaxed states.