Concept:
After death, the human body undergoes several predictable physical and chemical changes. These postmortem changes help forensic experts estimate the time since death.
Important postmortem changes include:
- Algor Mortis – Cooling of the body after death.
- Livor Mortis – Settling of blood in the lower parts of the body causing discoloration.
- Rigor Mortis – Stiffening of muscles after death.
- Putrefaction – Decomposition of body tissues due to bacterial activity.
Step 1: Understanding stiffening after death.
After death, chemical changes occur in the muscles due to depletion of ATP. As a result, the muscles become rigid and stiff.
Step 2: Identifying the correct term.
This postmortem stiffening of the body's joints and muscles is known as:
\[
\boxed{\text{Rigor Mortis}}
\]