Secondary flaccidity- due to breaking down of actinomycin due to putrefaction
Stiffening and shortening of muscles.
Mechanism: reduction of ATP. After death ATP is resynthesized for a short period of time depending upon the glycogen available locally, but after this glycogen is used up,ATP cannot be resynthesized. This leads to fusion of myosin and actin filaments into a dehydrated stiff gel resulting in condition known as RIGOR MORTIS.
It can be broken down by mechanical force.
It occurs in both voluntary and involuntary muscles. 1st body part to show rigor mortis is Heart.
Externally the first body part to show rigor mortis is Eyelids
Rule of 12: In india rigor mortis commences within 2-3 hrs,takes about 12 hrs to develop from head to toes, persist for another 12 hrs and takes about 12 hrs to pass off.
Rigor mortis in fetus develops after attaining 7 months of age.
As a general rule,the longer it takes to appear for rigor,the longer it lasts and vive versa.
In chronic diseases and convulsive disorders,rigor appears early and passes off quickly due to depletion of glycogen stores.In strychnine poisoning,rigor sets in almost immediately and passes off early.
In cases of sudden death,in healthy adults,a late onset and long duration is usual.
In death from drowning,rigor appears early due to muscular exhaustion but lasts longer due to coldness of water.
Rigor is frequently absent in septicemic conditions.
Surroundings effect:-Rigor is delayed by cold and accelerated by heat.
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