What phenomenon refers to the stiffening of skeletal muscles that occurs after death?

Rigor mortis is the phenomenon that describes the stiffening of skeletal muscles following death. This occurs as biochemical processes in the body halt and the muscles begin to lose their energy supply. ATP (adenosine triphosphate), which is necessary for muscle relaxation, depletes after death. Consequently, myosin heads remain bound to actin filaments in a state of contraction, leading to stiffness. This process typically begins a few hours after death and can last for several days until decomposition starts to occur, at which point rigor mortis dissipates as the muscle tissues break down.

Other terms such as cadaveric spasm and post-mortem rigidity may relate to changes in muscle tone after death but describe different specific processes or conditions. Cadaveric spasm refers to an immediate stiffening of muscles that may occur in certain stressful situations just before death. Muscle atrophy refers to the reduction in muscle mass over time, generally due to disuse or disease, and is not directly related to the post-mortem changes occurring after death. Understanding rigor mortis is crucial for forensic science and can aid in determining the time of death in an investigative context.