Yes, this whole zombie thing really is just an excuse for gratuitous nastiness. Here you can see its neck with the skin torn open, showing the neck muscles underneath. There's absolutely no reason to do that beyond me having a warped fascination with anatomy.
To get this effect I've made strips of muscle tissue just like I did for the face, and stuck them in place.
Afterwards, I've added skin over top of the muscle structure. The other side of the neck is intact, but it will still get some nasty scabby bits where the neck is severed.