After death (the third stage) Rigor Mortis occurs which is the stiffening of the muscles. It is caused by the chemical changes in the muscles after death.
Due to changes occured in cellular level all muscles in our body contract . our body experience infamous process of rigour mortis . When we are dead the cell organelles starts deteriorating thereby producing calcium into muscle cell , this causes stiffening of muscle cell .Our body keeps on contracting and ecpanding in live situation too , but because our brain no more orders to release , our muscles remain in same contracted position because of this .
