Rigidity of only group of voluntary muscles in a dead body is called:
a. Rigor mortis.
b. Cadaveric spasm.
c. Cold stiffening.
d. Heat stiffening.
e. Livor mortis.
The correct answer and explanation is:
The correct answer is a. Rigor mortis.
Rigor mortis refers to the postmortem stiffening of the muscles in a deceased body. It is the result of biochemical changes in the muscle fibers after death, leading to a temporary rigidity that can last for several hours to days. After a person dies, the body’s metabolic processes cease, which affects muscle cells in particular. In life, muscles contract and relax by using energy in the form of ATP (adenosine triphosphate). ATP is needed to detach the actin and myosin filaments in muscle fibers during relaxation. After death, ATP production stops, and the existing ATP is rapidly consumed. This leads to the actin and myosin filaments staying locked together, causing the muscles to remain contracted, resulting in rigidity.
Rigor mortis typically begins within 2 to 6 hours after death, first appearing in the smaller muscles, such as those in the face and hands, and then spreading to larger muscles. This stiffness is more prominent in colder environments because the body’s metabolic processes slow down. It generally peaks around 12 hours after death and starts to dissipate after about 48 to 72 hours as the muscle proteins begin to break down.
Other terms in the list have different meanings:
- Cadaveric spasm refers to an immediate and sudden stiffening of a muscle or group of muscles at the moment of death. It is typically seen in cases of violent death or intense physical effort before death.
- Cold stiffening is not a commonly used term but might be mistaken for rigor mortis in cold conditions.
- Heat stiffening does not exist as a recognized phenomenon related to death.
- Livor mortis refers to the pooling of blood in the lower parts of the body, causing a purplish discoloration of the skin after death.