Question

Which one is correct about the sequence of rigor mortis?

• A. Centre to periphery
• B. Head to foot
• C. Foot to head
• D. Simultaneously

Hint:

Rigor mortis begins in the small muscles of the face and progresses down the body, ending in the lower extremities.

Answer 1

The Correct Option is B

Step 1: Recall the biochemical driver of rigor mortis.
After death, ATP is no longer regenerated, so actin and myosin lock together and muscles stiffen. The smaller the muscle mass, the sooner its ATP is exhausted - so the order of stiffening follows muscle size, smallest first.

Step 2: Translate that into a body sequence.
The smallest muscle groups are in the face, jaw and neck, so stiffness appears there first. It then spreads to the trunk and limbs and reaches the larger muscles of the legs and feet last. This gives a top-down progression: head to foot (the descending pattern; Nysten's rule).

Step 3: Reject the other patterns.
• Centre to periphery - not how rigor spreads; it is governed by muscle size, not radial distance.
• Foot to head - reverses the true order, since the large foot/leg muscles stiffen last, not first.
• Simultaneously - incorrect, because differing muscle masses deplete ATP at different rates, giving a sequence rather than a single moment.

Step 4: Conclude.
Rigor mortis classically advances from head to foot.

Final answer: Option 2 - Head to foot.