Solution:
Rigor mortis is the state of rigidity that develops in the muscles after death. It is used to determine or estimate the time of death. This refers to the body's stiffening after death due to loss of Adenosine Triphosphate (ATP) from the body's muscles. ATP provides the energy to the muscles that help them work, and without this, the muscles become stiff and inflexible. Rigor mortis is possibly one of the most well known of the taphonomic changes and is the process that causes the muscles in the body to stiffen resulting in rigidity due to a range of chemical changes in the muscle structure. Muscle fibres, which in life move because of sliding filament theory, rely on ATP conversion to ADP. After death, when the respiration ceases, the intracellular pH decreases due to lactic and pyruvic acid production. The anaerobic glycolysis of glycogen in the muscles causes glycogen depletion and thus reduced ATP concentrations. Rigor mortis is the rigidity that develops in dying muscles as ATP becomes depleted and cross bridges remain attached can be relieved only by removal of Ca2+ and addition of ATP.
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