Rigor mortis starts in:

Ans: A (Heart) Ref: The Essentials of Forensic Medicine and Toxicology by KS Narayan Reddy. 29th edition. 2010Explanation:Rigor MortisThis is the state of stiffening and sometimes shortening of muscles following deathIt occurs due to lack of ATP after birth.When the ATP is reduced to a critical levels of 85% of normal, the overlapping portions of myosin and actin Filaments combine as rigid link of actomyosin. which is viscous and inextensible causing hardness and rigidity of muscles- Order of appearance: Heart (left) - eyelids facial muscles - neck and trunk - upper extremities - legs - muscles of fingers and toes.- it passes off in the same order. In India, it commences by 2-3 hrs, develops for 12 hrs. and usually lasts for 18-36 hrs in summer, and 24-48 hrs in winter.Time of Onset: In India, it begins 1 - 2 hours after birth.Duratin of RM: In India, it usually lasts for 24 - 36 hours during w inter and 16-24 hours during summer.Medico-legal ImportanceIt is a deFinite sign of deathIts extent helps in estimating the time since deathIt indicates the position of body at the time of deathConditions Simulating RMHeat stiffeningCold stiffeningCadaveric spasm or instantaneous rigiditySecondary RelaxationFlaccidity following RM is caused by action of the alkaline liquids produced by putrefaction.