Pain and agony are written onto the faces of mummies found world-wide, their mouths agape as if frozen mid-scream. Now one researcher has unlocked the reason why.
“This temporo-mandibular joint is fairly loose…. Unlike the tight ball-and-socket linking the leg and the hip, the jaw and cranium are held together only by ligaments and muscles. If unimpeded–by the position of the body, wrappings, or very fast desiccation–the jaw will drop down as the muscles relax and decompose after rigor mortis.”
So, how do morticians today keep their clients from screaming? Unlike their Victorian predecessors who employed a chinstrap, they use needle and thread. It is somewhere on the continuum between gross and disturbing, but if you really need to know, you can look at this website’s note about “Mouth Closure.”