Mouth/Teeth
The bite is the primary mode of attack for the living dead. As research has discovered, the teeth of a zombie are not anatomically identical to those of its formerly human self (see Combat Reports, Joseph Gartner.)
It is for this reason that a zombie showing considerable decomposition throughout the rest of its physical structure after years of weathering will still have most of its teeth intact. Analysis has shown, however, that the bite strength of the zombie is approximate to that of a normal human being - 170 pounds of pressure per square inch. Attempts at developing chemical or biological weapons to specifically address the zombie’s primary attack method have thus far been unsuccessful.
As such, the mouth of a zombie is clearly its most dangerous asset. Once within an effective attack range, a ghoul will attempt to bite any human flesh in closest proximity to its open maw. Any bite from a zombie that pierces human flesh, regardless of size or lethality, is a mortal wound, and will result in infection, death, and eventual reanimation into a member of the living dead.
There is a common misconception that the walking dead are only interested in devouring tissue originating from the human brain. This is inaccurate. Do not make the false assumption if you are wearing a piece of defensive headgear that you are insulated from the threat of a zombie bite. All undead ghouls crave living human tissue regardless of origin or location including, but not limited to, the epidermis, muscle tissue, internal organs and cerebral grey matter.