Rigor mortis occurs due to:
September 2008
a) Muscle of the body began to relax
b) Capillo-venous distension in the most dependent body parts
c) Muscle of the body began to stiffen
d) Mummification of the body tissues
Correct Answer - C
Ans. C: Muscle of the body began to stiffen
A few hours after the death, the joints of the body stiffen and
become locked in place. This stiffening is called rigor mortis.
Depending on temperature and other conditions, rigor mortis lasts
approximately 24- 48 hours in winter and 18-36 hours in summer.
The phenomenon is caused by the skeletal muscles partially
contracting. The muscles are unable to relax, so the joints become
fixed in place Rigor mortis can be used to help estimate time of
death.
The onset of rigor mortis may range from 1-2 hours, depending on
factors including temperature (rapid cooling of a body can inhibit
rigor mortis, but it occurs upon thawing). Maximum stiffness is
reached around 12-24 hours post mortem. It first starts in involuntary
muscles (myocardium)
Eyelids, neck and jaw muscles are affected first, with the rigor then
spreading to other parts of the body.
The joints are stiff but after some time general tissue decay and
leaking of lysosomal intracellular digestive enzymes will cause the
muscles to relax.