At what temperature does muscle stiffening commonly occur?

Muscle stiffening, also known as rigor mortis, typically begins to occur after a body reaches a temperature of around 60 degrees Fahrenheit. This process is part of the postmortem changes that happen in cadavers, where the muscles become rigid after death due to chemical changes in the muscle fibers.

At temperatures lower than this threshold, rigor mortis may not start because the chemical reactions that lead to muscle stiffening are inhibited. Above this temperature, the process of rigor mortis progresses more rapidly. Understanding the onset of rigor mortis is essential in forensic medicine for estimating the time of death, as it is influenced by the ambient temperature and other factors.

The other temperature options provided (50, 70, and 80 degrees) are either below or above the threshold for the typical onset of muscle stiffening. At these temperatures, the physiological processes related to rigor mortis would either not have started yet or would be in different stages of development, making them less relevant for determining when stiffening occurs postmortem.