Which term describes the postmortem muscle stiffening that begins after death?

Which term describes the postmortem muscle stiffening that begins after death?

• A. Remains
• B. Optical
• C. Petechiae
• D. Rigor Mortis

Answer: (D)

Rigor mortis is the postmortem muscle stiffening that begins after death. It happens because cellular respiration stops and ATP is depleted, so muscles can no longer detach the myosin heads from actin. As calcium leaks into the muscle cells and remains high without ATP to pump it back, cross-bridges stay formed, locking muscles in a rigid state. This stiffness typically starts a few hours after death, progresses to involve large and then all muscle groups, and then dissipates as enzymes break down muscle proteins over the next day or two. Temperature and the person’s condition before death can influence how quickly it appears and how long it lasts. The other terms don’t describe this process: they refer to different postmortem changes or findings not related to the muscle stiffening characteristic of rigor mortis.

Rigor mortis is the postmortem muscle stiffening that begins after death. It happens because cellular respiration stops and ATP is depleted, so muscles can no longer detach the myosin heads from actin. As calcium leaks into the muscle cells and remains high without ATP to pump it back, cross-bridges stay formed, locking muscles in a rigid state. This stiffness typically starts a few hours after death, progresses to involve large and then all muscle groups, and then dissipates as enzymes break down muscle proteins over the next day or two. Temperature and the person’s condition before death can influence how quickly it appears and how long it lasts. The other terms don’t describe this process: they refer to different postmortem changes or findings not related to the muscle stiffening characteristic of rigor mortis.