At what point does rigor mortis begin in muscle groups?

Rigor mortis typically begins in the small muscle groups, which include the muscles in the face, neck, and extremities. After death, the body undergoes various physiological changes, and rigor mortis is one of them, characterized by the stiffening of skeletal muscles due to biochemical processes.

This process starts in smaller, finer muscle groups because they succumb to the effects of rigor mortis more quickly than larger muscle groups. Initially, the small muscles show signs of stiffness before it moves on to larger muscles. Understanding this progression is critical for forensic investigations, as it helps in estimating the time of death.

In contrast, options that reference large muscle groups, heart muscles, or abdominal muscles are inaccurate regarding the onset of rigor mortis, as these areas stiffen later in the process and are not the first affected after death.