Cadaveric rigidity (Rigor mortis) | Cadaveric spasm | |
Production | Freezing and exposure to temperature above 65°C will produce rigor | Cannot be produced by any method after death |
Mechanism | Known. Reduction of ATP | Not clearly known |
Predisposing factor | Nil | Sudden death, excitement, fear, exhaustion, nervous tension, etc |
Time of onset | 1-2 hours after death | Instantaneous |
Muscles involved | All the muscles of the body, both voluntary and involuntary | Usually restricted to a single group of voluntary muscles |
Muscle stiffening | Not marked; moderate force can overcome it | Marked; very great force is required to overcome it |
Molecular death | Occurs | Does not occur |
Body heat | Cold | Warm |
Electrical stimuli | Muscles do not respond | Muscles respond |
Muscular reaction | Acidic | Alkaline |
Medicolegal importance | Indicates time of death | Indicates mode of death, i.e. suicide, homicide or accident |
Reference:
1. The Essentials of Forensic Medicine & Toxicology, 34th edition, Dr. K.S. Narayan reddy and O.P. murty, P. No. 155