what is it called when a dead body moves
Cadaveric spasm Cadaveric spasm, also known as postmortem spasm, instantaneous rigor, cataleptic rigidity, or instantaneous rigidity, is a rare form of muscular stiffening that occurs at the moment of death and persists into the period of rigor mortis.[1] Cadaveric spasm can be distinguished from rigor mortis being stronger stiffening of the muscles that can't be easily undone like rigor mortis.[2] The cause is unknown, but is usually associated with violent deaths happening under extremely physical circumstances with intense emotion.[3]