What term describes the phase where a body becomes rigid within a few hours after death?

The term that describes the phase where a body becomes rigid within a few hours after death is rigor mortis. This physiological process occurs as the muscles stiffen due to chemical changes in the muscle tissues following death. Specifically, after blood circulation ceases and ATP (adenosine triphosphate) production stops, muscles are unable to relax, leading to stiffness. Rigor mortis typically begins a few hours after death, reaches its peak rigidity around 24 to 48 hours, and then gradually dissipates as decomposition progresses.

In contrast, decomposition refers to the broader process of breakdown of the body after death, which involves various biological and chemical changes. Livor mortis pertains to the settling of blood in the lower parts of the body, which can cause discoloration of the skin. A contusion is a bruise resulting from localized bleeding under the skin due to trauma and is unrelated to the processes occurring after death.