The order of onset of rigor mois is:
**Core Concept**
The order of onset of rigor mortis is related to the **biochemical changes** that occur after death, particularly the depletion of **ATP (adenosine triphosphate)** in muscles. This process is influenced by the **metabolic rate** of different tissues.
**Why the Correct Answer is Right**
Rigor mortis typically begins in smaller muscles, such as those in the **face and hands**, and then progresses to larger muscle groups. This sequence reflects the varying rates of ATP depletion among different muscle types.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it doesn't accurately reflect the known sequence of rigor mortis onset.
**Option B:** Incorrect as it misrepresents the order.
**Option C:** Incorrect because the order doesn't align with observed post-mortem changes.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that rigor mortis can be influenced by **environmental factors** such as temperature, which affects the rate of ATP depletion.
**Correct Answer:** D. smaller muscles to larger muscles.