Cadaveric spasm
Cadaveric spasm, also known as postmortem spasm, instantaneous rigor mortis, 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. Cadaveric spasm can be distinguished from rigor mortis as the former is a stronger stiffening of the muscles that cannot be easily undone, while rigor mortis can. Muscles respond to electric stimuli and the muscular reaction is alkaline. The cause is unknown but is usually associated with violent deaths under extremely physical circumstances with intense emotion. Manifestation. Cadaveric spasm may  affect all muscles in the body, but typically only groups, such as the forearms, or hands. Cadaveric spasm is seen in cases of drowning victims when grass, weeds, roots or other materials are clutched, and provides evidence of life at the time of entry into the water. Cadaveric spasm often crystallizes the last activity one did before death and is therefore significant in forensic investigations, e.g. holding onto a knife tightly. Physiological mechanism. ATP is required to reuptake calcium into the sarcomere's sarcoplasmic reticulum (SR). When a muscle is relaxed, the myosin heads are returned to their "high energy