Home › MCQs › MBBS › Question #10236
Back to Questions
MBBS QUESTION #10236
Question 1
Rigor mortis, the stiffening of muscles after death, is best explained physiologically by:
  • Continued ATP-dependent cross-bridge cycling after death
  • Depletion of cellular ATP, which is required to detach myosin heads from actin, leaving cross-bridges locked in place✔️
  • Excessive calcium reuptake into an intact sarcoplasmic reticulum
  • Loss of troponin function alone, with normal ATP levels
Correct Answer Explanation
ATP is required not for cross-bridge formation but for detaching myosin from actin, allowing the cycle to reset. After death, ATP stores are depleted and calcium leaks uncontrolled into the sarcoplasm, allowing cross-bridges to form but never releasing — producing the sustained, irreversible-until-decomposition stiffness of rigor mortis.