Information related to the breakdown of the body after death, especially relevant if the body is kept at home for any length of time.
Once the heart stops beating, blood collects in the most dependent parts of the body (livor mortis), the body stiffens (rigor mortis), and the body begins to cool (algor mortis).
The blood begins to settle in the parts of the body that are the closest to the ground, usually the buttocks and back when a corpse is supine. The skin becomes pale as the blood drains into the larger veins. Within minutes to hours after death, the skin is discoloured by livor mortis, the purple-red discolouration from blood accumulating in the lowermost (dependent) blood vessels. Immediately after death, the blood is ‘unfixed’ and will move to other body parts if the body’s position is changed. After a few hours, the pooled blood becomes ‘fixed’ and will not move. Livor mortis is usually most pronounced eight to twelve hours after death. The skin, no longer under muscular control, succumbs to gravity, forming new shapes and accentuating prominent bones still further. The body then begins to cool.
At the moment of death, the muscles relax completely — a condition called ‘primary flaccidity.’ The muscles then stiffen, perhaps due to coagulation of muscle proteins or a shift in the muscle’s energy containers (ATP-ADP), in a condition known as rigor mortis. All of the body’s muscles are affected. Starting with the eyelids, neck, and jaw, rigor mortis begins within two to six hours of death. Over the next four to six hours, rigor mortis spreads to the other muscles, including those in the internal organs such as the heart. The onset of rigor mortis is more rapid if the environment is cold and if the decedent had performed hard physical work just before death. Its onset also varies with the individual’s age, sex, physical condition and muscular build.
After being in this rigid condition for twenty-four to eighty-four hours, the muscles relax and secondary laxity (flaccidity) develops, usually in the same order as it began (see Table below). The length of time rigor mortis lasts depends on multiple factors, particularly the ambient temperature. Many infant and child corpses will not exhibit perceptible rigor mortis. This decreased perceptible stiffness may be due to their smaller muscle mass.