Rigor Mortis
Definition
The post-mortem stiffening of muscle from ATP depletion and actin-myosin cross-linking. Develops over hours, peaks, and resolves with putrefaction.
- Onset
- 1 to 2 hours after death
- Full development
- 8 to 12 hours
- Duration
- Resolves over 24 to 36 hours
- Cause
- ATP depletion and actin-myosin cross-linking
Common questions
How long does rigor mortis last?+
Rigor mortis typically starts 1 to 2 hours after death, reaches full stiffness by 8 to 12 hours, and gradually disappears over 24 to 36 hours as putrefaction breaks down the muscle tissue.
What causes the muscles to stiffen after death?+
After death, muscles run out of ATP, the energy molecule they need to relax. Without ATP, actin and myosin filaments lock together and stay contracted, creating the characteristic stiffness.
Why does rigor mortis eventually go away?+
Putrefaction, the decomposition process, breaks down muscle tissue and the actin-myosin cross-links, so the body gradually becomes limp again.
Related terms
- Algor Mortis
- Postmortem cooling of the body toward ambient temperature, approximately 1-1.5 degrees Celsius per hour under average conditions. Used alongside other postmortem changes...
- Henssge Nomogram
- A graphical method using rectal temperature, ambient temperature and body weight to estimate PMI within a 95 percent confidence interval, with correction...
- Post-Mortem Interval (PMI)
- The time elapsed between death and discovery or examination of remains. PMI estimation draws on multiple disciplines: soft tissue decomposition stage, insect...
- Adipocere
- A waxy, soap-like substance formed by saponification of body fat under anaerobic, wet, cool-to-moderate conditions. Replaces unsaturated fatty acids with saturated palmitic...
- Autopsy
- Systematic external and internal examination of a dead body to find cause, manner and time of death. Ordered under BNSS 2023 Section...
- Cadaveric Spasm
- Instantaneous rigor without a flaccid phase, locking the muscle group active at death (clutched weapon, grass).
- Decomposition
- Autolysis (intracellular enzymes) plus putrefaction (bacterial breakdown). Greenish discoloration starts over the right iliac fossa.
- Livor Mortis
- Postmortem pooling of blood in dependent tissues producing a purple-red discolouration. Becomes fixed at roughly 8-12 hours; discordance between liver position and...
- Livor Mortis (Hypostasis)
- Bluish-purple settling of blood in dependent parts. Begins 30 minutes to 2 hours, fixed by 8 to 12 hours.
- Marbling
- Greenish-black branching pattern over superficial veins from haemoglobin plus H2S. 24 to 48 hour sign.
- Mummification
- Preservation of the body by desiccation rather than liquefaction, occurring when surface evaporation rate exceeds the rate of putrefaction gas production. Common...
- Putrefaction
- Decomposition of tissues by microorganisms, principally anaerobic bacteria from the gastrointestinal tract. Products include hydrogen sulphide, methane, ammonia, and putrescine, which cause...
Explained in these topics
- Time Since Death: PMI, Henssge Nomogram, Tropical CorrectionThe post-mortem stiffening of muscle from ATP depletion and actin-myosin cross-linking. Develops over hours, peaks, and resolves with putrefaction.
- Post-Mortem Examination, Post-Mortem Changes and Time Since DeathPost-mortem stiffening from ATP depletion. Onset 1 to 2 hr, full 8 to 12 hr, passes off 24 to 36 hr.