What phenomenon occurs as the muscles stiffen after death?

Rigor mortis is the phenomenon that occurs as the muscles stiffen after death. This natural process is due to biochemical changes within the muscle tissue following the cessation of circulatory and metabolic functions. When the heart stops beating, the body’s cells begin to break down, and energy (ATP) stores within the muscles are depleted. This depletion prevents muscles from relaxing, leading to the stiffness characteristic of rigor mortis.

The onset of rigor mortis typically occurs several hours post-mortem, initially affecting smaller muscles in the face and neck before spreading to the larger muscle groups. This process is an important factor in forensic investigations, as it helps estimate the time of death based on the degree of stiffness and its progression throughout the body.

Other phenomena, like hypostasis, livor mortis, and cadaveric spasm, relate to different physiological changes that occur after death, but they do not describe the specific stiffening of the muscles. Hypostasis refers to the settling of blood under the influence of gravity, while livor mortis denotes the pooling of blood in the lowest parts of the body, creating a purplish coloration. Cadaveric spasm is an immediate stiffening of the muscles at the time of death, typically associated with