## **Core Concept**
Rigor mortis is a well-known post-mortem change that occurs in the muscles of a deceased individual, causing temporary stiffening. It is a result of changes in the muscle cells and adenosine triphosphate (ATP) depletion. The process involves the interaction of actin and myosin filaments.

## **Why the Correct Answer is Right**
The correct answer, **Eyelids**, is right because rigor mortis typically begins to set in around 2 hours after death and starts in smaller muscles, such as those in the **eyelids**, face, and neck, before progressing to larger muscles. The smaller muscles are the first to be affected due to their higher surface-to-volume ratio and possibly higher metabolic rate.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, while larger muscles do experience rigor mortis, they are not the first to be affected.
- **Option B:** This option is incorrect as there is no commonly recognized association of rigor mortis starting in this specific area as the first.
- **Option C:** This option is incorrect because, although muscles are indeed involved in rigor mortis, specifying "muscles" is too broad and does not accurately reflect the sequence or specificity of muscle groups affected.
- **Option D:** This option is incorrect as there is no widely acknowledged initial site of rigor mortis by this description.

## **Clinical Pearl / High-Yield Fact**
A memorable point for exams is that rigor mortis usually starts within 2 hours after death, initially affecting smaller muscles like those of the **eyelids** and face. A classic clinical correlation is that the process can make it difficult to determine the time of death accurately but generally follows a somewhat predictable pattern.

## **Correct Answer:** . **Eyelids**