Natural stiffening of muscles after death is known as?

Ans. is 'b' i.e. Rigor mortis Rigor mortiso It is defined as contraction, stiffening, shortenig and opacity of muscles after death.o It occurs after molecular (cellular) death. In tropical countries (e.g. india), it begins 1-2 hours after death, takes further 2 hours to develop, and lasts for 18-36 hours in summer and 24-48 hours in winter.o In temperate countries, it begins in 3-6 hours, takes further 2-3 hours to develop and lasts for 2-3 days.o All muscles of body are involved, i .e. voluntary or involuntary.o However, it does not start in all muscles simultaneously (nysten's rule).o Involuntary muscles (heart) are involved first than voluntary muscles.o Sequence of muscles involvement is as follows : Heart > upper eyelid > neck > jaw > face > chest > upper limb > abdomen > lower limb > finger and toes.o It passes off in the same order in which it has appeared.Note:o Cadaveric spasm is not natural stiffening. It is defined as the condition wherein a group of muscles, which were in contraction or spasm at the time of death, continue to be in spasm even after death, without the stage of primary relaxation. It does not occur in all deaths (unlike rigor mortis, which occurs in all deaths).