What is the Difference Between Rigor Mortis and Cadaveric Spasm?

Rigor mortis and cadaveric spasm are two postmortem changes that affect the muscles of the body. Here are the key differences between the two:

1. Occurrence: Rigor mortis begins 2 to 3 hours after death and lasts for up to 24 hours, while cadaveric spasm occurs at the moment of death and persists into the postmortem period.
2. Stiffening: Rigor mortis causes the stiffening of all types of muscles, whereas cadaveric spasm is a stronger stiffening of the muscles that cannot be easily undone.
3. Muscle Involvement: Rigor mortis affects all muscles, whereas cadaveric spasm occurs only in a selected group of muscles.
4. Timing: A cadaveric spasm always takes place before rigor mortis, and a body past the rigor mortis state will not experience a cadaveric spasm.
5. Purpose: While rigor mortis provides information about the time since death, cadaveric spasm is valuable in commenting on the manner of death.

In summary, rigor mortis is a well-known postmortem change that affects all muscles and occurs after death, while cadaveric spasm is a rare, stronger stiffening of selected muscles that takes place at the moment of death and is useful for determining the manner of death.

Comparative Table: Rigor Mortis vs Cadaveric Spasm

Here is a table comparing the differences between rigor mortis and cadaveric spasm:

In summary, rigor mortis is a postmortem stiffening of body muscles that occurs in all types of death, while cadaveric spasm is a rare form of muscle stiffening associated with violent or emotionally intense deaths. Rigor mortis helps estimate the time of death, while cadaveric spasm can provide information about the last activity the person did before dying.