Which term describes the stiffening of body muscles caused by chemical changes within muscle tissue?

• A. Rigor mortis
• B. Algor mortis
• C. Putrefaction
• D. Abandonment

Answer: (A)

Postmortem muscle stiffening is driven by chemical changes inside muscle tissue after death. When circulation and oxygen stop, cells run out of ATP, and calcium ions accumulate in the muscle fibers. Without ATP to power relaxation, the myosin heads latch onto actin and form cross-bridges that cannot detach. This creates a rigid, contracted state known as rigor mortis. Over time, enzymes and decomposition break down these proteins, and the stiffness gradually disappears.

Algor mortis refers to the body's cooling after death, not stiffness. Putrefaction is the decay process caused by bacteria. The fourth term isn’t a standard term for this phenomenon and doesn’t describe the chemical stiffening that occurs in muscle tissue after death.