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RIGOR MORTIS 
ROHAN DEOKAR
Contents 
 Basic Definition 
 Nysten’s Law 
 Physical Changes 
 Biochemistry/Mechanism 
 Applications 
 Further Note...
Basic Definition 
 Rigor mortis (Latin: rigor "stiffness", mortis "of death") is one of 
the recognizable signs of death,...
Nysten’s Law 
 In 1812, a French pediatrician named Pierre Nysten 
recorded his observation that rigor mortis follows a 
...
Physical Changes 
 At the time of death, a condition called "primary flaccidity" 
occurs. Following this, the muscles sti...
Biochemistry/Mechanism 
 The phenomenon is caused by the skeletal muscles 
partially contracting. The muscles are unable ...
Contd…… 
 After death, cellular respiration in organisms ceases to occur, 
depleting the corpse of oxygen used in the mak...
Contd….. 
 Unlike normal muscular contraction, after death, the body is 
unable to complete the cycle and release the cou...
Applications 
 The degree of rigor mortis may be used in forensic pathology to 
determine the approximate time of death. ...
Further Notes 
 Contrary to common perception the process of rigor 
mortis actually does reverse and the body returns to ...
Table Guide 
Body temp Body stiffness Time since death 
warm not stiff dead not more than three 
hours 
warm stiff dead 3 ...
Thank You !!!!!!!
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Rigor mortis

A basic description of rigor mortis, its significance, causes , applications & reference chart.

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Rigor mortis

  1. 1. RIGOR MORTIS ROHAN DEOKAR
  2. 2. Contents  Basic Definition  Nysten’s Law  Physical Changes  Biochemistry/Mechanism  Applications  Further Notes  Table Guide
  3. 3. Basic Definition  Rigor mortis (Latin: rigor "stiffness", mortis "of death") is one of the recognizable signs of death, caused by chemical changes in the muscles after death, causing the body to stiffen and locked in place, making it difficult to move or manipulate.  It commences after about 3 to 4 hours, reaches maximum stiffness after 12 hours, and gradually dissipates from approx 24 hours after death, thus lasting for about 72 hours.  This phenomenon progresses in a downward, head-to-toe direction. In 12 to 18 hours the body is, as the saying goes, stiff as a board. At this stage, the joints can be moved only by force, breaking them in the process.  It takes about two days for rigor mortis to fade, and once it does, decay sets in. If the body isn't embalmed or cooled to 38 degrees Fahrenheit (3.3 degrees Celsius) or below, it will quickly decompose.
  4. 4. Nysten’s Law  In 1812, a French pediatrician named Pierre Nysten recorded his observation that rigor mortis follows a downward path that begins in the upper region of the body, around the face and head, and travels in a set pattern down to the rest of body and the extremities.  Known as Nysten's law, this principle likely reflects the fact that rigor mortis - while affecting all muscles in the same way at the same time - becomes noticeable first in small muscle groups, such as those around the eyes, mouth and jaws, and becomes pronounced somewhat later in the larger muscles of the lower limbs.
  5. 5. Physical Changes  At the time of death, a condition called "primary flaccidity" occurs. Following this, the muscles stiffen in rigor mortis. All muscles in the body are affected.  Starting between two to six hours following death, rigor mortis begins with the eyelids, neck, and jaw. The sequence may be due to different lactic acid levels among different muscles, which is directly related to the difference in glycogen levels and different types of muscle fibers.  Rigor mortis then spreads to the other muscles within the next four to six hours, including the internal organs.  The onset of rigor mortis is affected by the individual's age, sex, physical condition, and muscular build. Rigor mortis may not be perceivable in many infant and child corpses due to their smaller muscle mass.
  6. 6. Biochemistry/Mechanism  The phenomenon is caused by the skeletal muscles partially contracting. The muscles are unable to relax, so the joints become fixed in place.  What happens is that the membranes of muscle cells become more permeable to calcium ions.  Living muscle cells expend energy to transport calcium ions to the outside of the cells.
  7. 7. Contd……  After death, cellular respiration in organisms ceases to occur, depleting the corpse of oxygen used in the making of adenosine triphosphate (ATP) allowing the corpse to harden and become stiff.  ATP is no longer provided to operate the SERCA pumps in the membrane of the sarcoplasmic reticulum, which pump calcium ions into the terminal cisternae.  This causes calcium ions to diffuse from the area of higher concentration (in the terminal cisternae and extracellular fluid) to an area of lower concentration (in the sarcomere), binding with troponin and allowing for crossbridging to occur between myosin and actin proteins, two types of fibers that work together in muscle contraction.
  8. 8. Contd…..  Unlike normal muscular contraction, after death, the body is unable to complete the cycle and release the coupling between the myosin and actin, creating a state of muscular contraction.  The muscle fibers ratchet shorter and shorter until they are fully contracted or as long as the neurotransmitter acetylcholine and the energy molecule ATP are present.  However, muscles need ATP in order to release from a contracted state (it is used to pump the calcium out of the cells so the fibers can unlatch from each other).  ATP reserves are quickly exhausted from the muscle contraction and other cellular processes. This means that the actin and myosin fibers will remain linked until the muscles themselves start to decompose.  As part of the process of decomposition, the myosin heads are degraded by the enzymes, allowing the muscle contraction to release and the body to relax.
  9. 9. Applications  The degree of rigor mortis may be used in forensic pathology to determine the approximate time of death. A dead body holds its position as rigor mortis sets in.  If the body is moved after death, but before rigor mortis begins, forensic techniques such as Livor mortis can be applied.  If the position in which a body is found does not match the location where it is found (for example, if it is flat on its back with one arm sticking straight up), that could mean someone moved it.  Several factors also affect the progression of rigor mortis, and investigators take these into account when estimating the time of death.  One such factor is the ambient temperature. When conditions are warm, the onset and pace of rigor mortis are sped up by providing a conducive environment for the metabolic processes that cause decay. Low temperatures, however, slow them down. Therefore, for a person who dies outside in frozen conditions rigor mortis may last several days more than normal, so investigators may have to abandon it as a tool for determining time of death.
  10. 10. Further Notes  Contrary to common perception the process of rigor mortis actually does reverse and the body returns to a flaccid state; the muscles losing their tightness in the reverse of how they gained it: i.e. those larger muscles that contracted last will lose their stiffness first and return to their pre-rigor condition.  Rigor mortis is a good means of indicating time of death as is normally visible within the first thirty-six to forty-eight hours after death; after which it leaves the body.
  11. 11. Table Guide Body temp Body stiffness Time since death warm not stiff dead not more than three hours warm stiff dead 3 to 8 hours cold stiff dead 8 to 36 hours cold not stiff dead more than 36 hours
  12. 12. Thank You !!!!!!!

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