Return of the Living Dead/Headscratchers

How on earth is that completely skeletal zombie (Not Tarman, the one that rises out of the grave) even able to move?
- The same way a headless one can move. This random irregularity is a large reason why the Return films are generally regarded as worse than the ____ Of The Dead films by Romero.
  - George Romero has nothing to do in any way with the Return of the Living Dead series. They were made by someone else entirely exploiting the fact that Night of the Living Dead was public domain.
- Or, alternatively, are regarded as a lot more fun than the Romero films, because they're focused on zombie horror and dark comedy than beating you over the head with "Humans are real monsters! Humans are suck! You die! You die to zombies who are better than you!"
How are the skeletal zombies even able to move? For that matter, is there even any bit of a brain left for the Trioxin gas to affect?
- And how is it that zombies without lips (Tarman, Lady Torso Zombie) are able to to make "M," "B" and "P" sounds when they speak?
- Also, in the fourth film, why did they make a "minimum security area" for zombies?
- Why do zombies seeking brains go after horny teenagers in a horror movie?
  - Because the endorphins, adrenaline, and other "feel-good" chemicals that the brains produce would probably be overflowing in the brains of horny and drugged-out teenagers. The zombies are in constant pain from rotting, and only human grey matter can ease their suffering. If you were in constant pain, wouldn't you want the best pain-killers that you could get your hands on? Not only that, they're so easy to obtain!