Which of the following is the Nysten’s law
**Core Concept**
Nysten's law describes the pattern of cadaveric rigidity (postmortem rigidity) in the human body, detailing the sequential involvement of muscle groups after death. It reflects the progressive stiffness due to muscle contraction and chemical changes in tissues following death.
**Why the Correct Answer is Right**
Nysten's law states that cadaveric rigidity develops in a specific, predictable sequence: first affecting the masticatory muscles, then facial and neck muscles, followed by trunk and arm muscles, and finally the lower limbs. This progression is due to the gradual accumulation of rigor mortis in muscle fibers, which is influenced by temperature, time, and body composition. The sequence is consistent and observable in forensic autopsies, making it a key principle in postmortem examination.
**Why Each Wrong Option is Incorrect**
Option A: Cadaveric rigidity does appear in hot humid conditions — it actually appears **slower** in such environments due to increased muscle relaxation, not absence.
Option B: Rigor mortis appears **earlier** in middle age due to higher muscle mass and metabolic activity, not in young or old — the statement is factually incorrect.
Option C: There is no evidence that rigidity occurs earlier in men than women — gender differences are minimal and not supported by clinical data.
**Clinical Pearl / High-Yield Fact**
Remember: Nysten’s law is about **sequence**, not gender, age, or climate. Always start with the masticatory muscles and progress down the body — this helps in estimating time of death in forensic investigations.
✓ Correct Answer: D. Cadaveric rigidity affects successively the masticatory muscles, those of the face and the neck, those of the trunk and arms and finally those of lower limbs rruk