Rigor Mortis
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Transcript of Rigor Mortis
MUSCULAR CHANGES
1. PRIMARY FLACCIDITY2. RIGOR MORTIS / CADAVERIC RIGIDITY3. SECONDARY RIGIDITY/RESOLUTION
PRIMARY FLACCIDITY
• Somatic death• Contact flattening• Muscle irritability &response to mech/elect
stimuli persists• Peristalsis ,ciliary movements, WBC movements
may be present • Focal twitching +nt-dying neurons• Loss of sphineter tone• Muscle protoplasm slightly alkaline
RIGOR MORTIS
• Rigor mortis is the stiffening of muscles after death.• In forensic pathological practice, the intensity of
rigor mortis is assessed on a pure subjective basis, meaning whether skeletal muscles offer resistance when joints are moved (flexion/extension).
• Post-mortem rigidity is characterized by a loss of muscle elasticity and plasticity, an increase in stiffness, and shortening of muscle length.
Phases of rigor mortis
1st phase -delay period2nd phase -onset phase(reversible)3rd phase-rigor(irreversible)4th phase -resolution
MECHANISM OF RIGOR MORTIS• It is a physico-chemical change in muscles due to lack of oxygen• Muscles are composed of myofibrils, which are again composed of myofilaments.• Two types of myofilaments : actin and myosin• Under the influence of adenosine triphosphate (ATP), actin and myosin form a contractile
compound, actomyosin.• With decrease of ATP levels post-mortem(85%), actin and myosin enter into a nonshiftable
and rigid state of adhesion until, under the influence of autolysis and putrefaction, protein disintegration of the myofibrils leads to loosening of rigor mortis (secondary relaxation)
• Maximum rigidity at ATP levels of 15%• Lactic acid -.3%• Sources of ATP-1)Phosphagen system 2)glycogen-lactic acid system 3)aerobic system • Onset of rigor mortis is earlier and more rapidly progressing in red muscles than in white
muscles, which has been attributed to ATP levels falling more rapidly after death in red muscles than in white muscles
ORDER OF APPEARANCE
• Shapiro-Rigor mortis develops in all muscles at the same time and at the same speed. However, because of the different diameters of the muscles involved, post-mortem rigidity becomes noticeable at first in smaller muscle groups
• Nysten’s rule-descends from the head to the shoulder girdle and arms and then to the legs, greater diameter of the muscle groups located at joints that are located farther downwards the body and disappears in the same order in which it has appeared
Time of onset and duration
Time of onset• India
begins 1-2hrs after death further 1-2hrs to develop• Temperate countries begins 3-6hrs after death further 2-3hrs to develop
Duration• India winter-lasts 24-48hrs summer-lasts18-36hrs• Temperate regions 2-3days
Testing of rigor mortis
-lifting of eyelids-depressing jaw-bending of neck and joints
Post mortem changes
• Heart -Myocardial hypertrophy -ante mortem dilatation/myocardial deg -systolic/diastolic stoppage • Skin –cutis anserina/goose skin• Testes drawn up• Seminal ejections• Expelling of fetus from uterus
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Factors affecting rigor mortis
Early onset• Cholera, typhoid, TB, cancer• firearms, electro, lightning• cutthroat• Strychnine poisoning• OP poisoning• CO poisoning –delays
disappearance• Cold weather• Children and old people
Late onset• Asphyxia• Sev hemorrhage• Apoplexy• Pneumonia• Nervous disease• Normal saline perfusion• Resting and healthy
muscles
Early disappearance• Strychnine poisoning• Bact inf –gas gangrene• Children and old people
Late disappearance• CO poisoning• Healthy and resting
muscles• Cold weather
Absent rigor mortis • Fetus of less than 7 months of age• Septicemia • Advanced states of multiple sclerosis,
amyotrophic lateral sclerosis, or Duchenne muscular atrophy
Medico legal importance• Helpful in determining whether a body has been moved after death. If a body is found in
an illogical posture, this means a body position that would not have been maintained under the influence of gravity (primary relaxation of the muscles after death), this position implies that the body has been moved after the development of rigor mortis
• Examination of the palms and the inside aspects of the fingers becomes difficult so that current marks or defence injuries located here may be overlooked
• In infants and children, a marked dilation of the anal orificium may be observed post-mortem . As mentioned before, immediately as death occurs and preceding the onset of rigor mortis, the whole body musculature loses its tone. In children a dilated anal orificium (because of the loss of tone of the musculature immediately as death occurs) may be fixed by rigor mortis, and this finding may even persist after rigor mortis has faded. Therefore, anal dilation alone is not a sufficient marker for penetrative anal abuse of children prior to death
• Muscle relaxation immediately after death with opening of the eyes and the mouth with subsequent fixation in rigor mortis may give the face a somehow grimace-like look post-mortem. However, one cannot predict from the face of a deceased, as often assumed by the unaware, whether this individual’s last moments were of fear or fright
CONDITIONS SIMULATING
1. Heat stiffening2. Cold stiffening3. Cadaveric spasm
Heat stiffening
• >650 C• More marked than that found in rigor mortis• Depends on intensity and duration for which
applied• Burning ,high voltage electric shock, fall into hot
liquid• Mechanism- denaturation and coagulation of
muscle protein• Cooked meat appearance
Cold stiffening
• Due to freezing of body fluids and solidification of subcutaneous fat
• When forcefully flexed-ice cracking in synovial fluid
• If again placed in warm temp-rigor appears rapidly and passes off quickly
• Medicolegal importance-subcut fat hardening in infants simulates ligature mark
Cadaveric spasm/Instantaneous rigor
• Complete rigor mortis occuring at the moment of deathand involving a hand ,limbor even an entire body
• No stage of primary relaxation
• Single group of voluntary muscle
Causes ,mechanism and MLI
• Suddendeath• Excitement• Fear • Severe pain• Exhaustion• Cerebral haemorrhage• Firearm wounds of head• Convulsant poisons
• Mechanism – 1.Neurogenic, 2.Adrenocortical exhaustion
• Medicolegal importance-
1.Weapon2. Material evidence 3.Antemortem drowning