What is rigor mortis?

Rigor mortis refers specifically to the stiffening of muscles and joints that occurs after death. This physiological process is caused by the lack of ATP (adenosine triphosphate), which is necessary for muscle relaxation. After death, muscles contract and become rigid, beginning typically a few hours after death and lasting up to several days, depending on environmental factors.

The onset and duration of rigor mortis can provide important information about the time of death in forensic investigations. Understanding this condition can help forensic scientists establish a timeline and assess the circumstances surrounding a death.

The other options involve different post-mortem processes that do not define rigor mortis. For instance, cooling of the body after death pertains to algor mortis, and pooling of blood refers to livor mortis, both of which help in estimating the time of death as well but are distinct physical changes. Decomposition involves various processes that occur after death, including rigor mortis, but is not synonymous with it.