Heads are part of a subcategory of zombie called partials. This means that some part of the body, usually a limb, is missing. However in extreme cases the entire lower half or large parts of the body could be missing. Heads are the extreme case gone even further. They are all that’s left when a zombie has been decapitated. They typically don’t last long and as I’ve labeled in the illustration they aren’t very good biters since they are missing most of their muscles which would control the movement of the jaw. Though they are less dangerous than full bodied zombies or even other partials, they are still more dangerous than one might thing. All it takes is one clumsy idiot playing around with one, getting all cocky and screwing up to the extent that he get’s himself bit. You don’t want to be that guy, do you? No. Didn’t think so.
Also, watch out for these guys being kept in jars. Some power hungry survivors make a habit of keeping nasty things like these around the house. Definitely NOT your grandmother’s preserves.