The term Rigor Mortis defines the state of a body that has died, and the stiffening of the joints, and is Latin for ‘Stiffness of Death’.When a person dies, the joints become stiff and lock into place. Rigor Mortis usually lasts 72 hours.

Rigor mortis can be used in Forensic Pathology to help estimate time of death. The onset of rigor mortis may range from 10 minutes to several hours, depending on factors including temperature (rapid cooling of a body can inhibit rigor mortis, but it occurs upon thawing).
Heat such as that from a fire can speed up the onset of Rigor Mortis.


Maximum stiffness is reached around 12-24 hours post mortem. Facial muscles are affected first, with the rigor then spreading to other parts of the body.

The joints are stiff for 1-3 days, but after this time general tissue decay causes the muscles to relax.

After death, respiration in organisms ceases to occur, depleting the corpse of oxygen used in the making of Adenosine triphosphate (ATP). ATP is no longer provided to operate the SERCA pumps in the membrane of the sarcoplasmic reticulum, which pump calcium ions into the terminal cisternae.

This causes calcium ions to diffuse from the area of higher concentration (in the terminal cisternae and extracellular fluid) to an area of lower concentration (in the sarcomere), binding with troponin and allowing for crossbridging to occur between myosin and actin proteins.

Unlike normal muscle contractions, the body is unable to complete the cycle and release the coupling between the myosin and actin, creating a perpetual state of muscular contraction.

So that is what Rigor Mortis is, and what it is caused by. It is worth noting that Rigor is very important in the food industry as not only does it have a major part to play in the preperation of fresh meats, it can also make fresh meat, such as steaks, much more tender and succulent after Rigor has passed.

I wonder if Hannibal the Cannibal had Rigor in mind when he prepared his victims…



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