Cadaveric rigidity or Cadaveric spasm is stiffness of muscles with immediate onset after death. This stiffness, unlike rigor mortis, does not pass through the stage of primary flaccidity.
Deceased may present with items held tightly in his palms resulting from sudden stiffness of voluntary muscles. It is believed that cadaveric spasm occurs in individuals who are at high levels of emotional or physical stress at the time of death. Although the exact mechanism of causation of cadaveric spasm is not known, many hypothesis on neurogenic phenomena have been put forward.