If early rigidity is observed in facial muscles, this supports which law?

• A. Nysten's law
• B. Glaister's law
• C. Coriolis law
• D. Guy's law

Answer: (A)

The main idea is the pattern in which rigor mortis appears. Observing rigidity in facial muscles early fits with Nysten's law, which says rigor mortis begins in the face and neck and then progresses to the trunk and limbs. This happens because after death ATP is depleted, allowing actin–myosin cross-bridges to lock and stiffen the muscles, and smaller, highly active facial muscles tend to go rigid first. The other options describe different ideas (for example, time-since-death estimation from temperature) and don’t explain why facial muscles would show early rigidity.