At first a body relaxes completely, then after three or four hours the small muscles of the eyelids, face and neck begin to stiffen. Rigor progresses downwards, from head to toe towards the larger muscles. After twelve hours the body is completely rigid and will stay fixed in the position of death for around twenty-four hours. Then the muscles gradually relax and stiffness goes away in the order in which it appeared, starting with the smaller muscles and progressing to the larger ones. After a further twelve hours or so all the muscles reach a state of complete relaxation.
