What is rigor mortis?

Rigor mortis is a phenomenon that occurs after death, specifically characterized by the stiffening of muscles. This condition results from biochemical processes that take place in the body once the heart has stopped beating and circulation ceases. Following death, the muscles are no longer supplied with oxygen, leading to a depletion of ATP (adenosine triphosphate), which is necessary for muscle relaxation. As a result, muscles stiffen and harden, typically beginning a few hours after death and lasting for several days before the body begins to decompose.

In contrast to other options: the first option describes a state of confusion, which is not related to the physical changes after death. The second option references a legal process related to a postmortem examination but does not pertain to the physiological changes that occur in the body. The fourth option relates to the emotional aspect of dealing with loss and is unrelated to the physical changes in the body after death. Therefore, the definition of rigor mortis aligns precisely with the condition of muscle rigidity that develops following death.