PRESENTER:

DR.RAJKUMAR. M.G.

PG IN FORENSIC

MEDICINE

SDUMC,KOLAR

DR.KIRAN.J

Prof . &HOD

DEPT. OF FORENSIC

MEDICINE

SDUMC,KOLAR

RIGOR MORTIS

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MODERATOR:

Rigor mortis (Latin: rigor "stiffness", mortis "of death")

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Also called as DEATH STIFFENING,CADAVERIC RIGIDITY

RM is one of the recognizable signs of death, caused by Physiochemical changes in the muscles(voluntary+involuntary) after death, causing the limbs of the corpse to become stiff ,shortening of muscle fibres.and difficult to move or manipulate .

In humans, it commences after about two to six hours, reaches maximum stiffness after 12 hours, and gradually dissipates from approximately 24 hours after death. Depending on temperature and other conditions, rigor mortis lasts approximately 72 hours.(Rule of 12).

MECHANISM/PATHOPHYSIOLOGY:

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Death

cessation of respiration

depletion of oxygen used in making of ATP

ATP no longer provided to operate the SERCA pumps in the membrane of the sarcoplasmic reticulum,which pump calcium ions into the terminal cisternae

calcium ions diffuse from the terminal cisternae and extra cellular fluid to the sarcomere

Calcium binds with Troponin

Crossbridging between myosin and actin filaments.

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Unlike normal muscle contractions,the body is unable to complete cycle and release the coupling between the myosin and actin,creating a perpetual state of muscular contraction,until the breakdown of muscle tissue by digestive enzymes during decomposition.

MECHANISM/PATHOPHYSIOLOGY:(contd)

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Signal from NERVOUS SYSTEM to contract MUSCLE

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Muscle-->Myofibril-->Sarcomere(contractile unit)

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Myosin-Thick filament/ATP dependent

motor protein.

Actin-Thin filament/Contractile filament

Of muscle cells.

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Thick filaments- Myosin are anchored to M line(center)

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Actin filaments are anchored to outer edge of Sarcomere-Z Line

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Myosin pulls Actin filaments along its length:

POWER STROKE

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Sliding filament mechanism:

Lengths of filaments do not change

Sarcomere shortens

Causes shortening of muscle fiber and muscle

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SUPPLY OF ATP IN MUSCLES DURING LIFE:

1. Phosphagen System

2. Glycogen-lactic acid system

3. Aerobic system.

ATP is responsible for elasticity and plasticity of muscle during life.

ATP hydrolysis=ADP+Inorganic phosphate

*Hydrolysis energy=>Power stroke action of Myosin.

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Muscle contractions are controlled by Calcium ions

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At RELAXED STATE:

Tropomyosin blocks CROSSBRIDGES,

Regulatory Proteins on Actin :TROPONIN and TROPOMYOSIN

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When calcium levels are high enough and ATP is present ,

Calcium binds to Troponin and displaces Tropomyosin and

Helps in formation of Cross bridges.

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Neuromuscular junction

Signal from Nervous system to CONTRACT=>Calcium

Released from sarcoplsamic reticulum.

T-tubule(myofibril)======>>>CALCIUM released.

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Muscle contraction

Z-Lines draw close to M –Lines=shortening of muscle fiber

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Rigor mortis -VIDEO

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AFTER DEATH:

PHYSIOCHEMICAL CHANGES IN MUSCLE

ATP is progressively and irreversibly destroyedaccumulation

of lactates and phosphates in muscles.

No Resynthesis of ATP

Postmortem SARCOPLASMIC DISRUPTION Flooding of

Calcium Ions into SARCOMERES Initiating the binding of

Actin and Myosin MIMICKING NORMAL CONTRACTION.

Rigor Mortis sets in when ATP is reduced to a critical level(85% of

-normal).Rigidity is MAXIMUM when ATP depletion is 15%.

Rigormortis is lost when putrefaction starts Proteolytic detachment

Loss of Structural Integrity muscles soften and relax.

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ORDER OF APPEARANCE:

Nysten’s Rule:Rigormortis does not start in all muscles

simultaneously.

Shapiro(1950):Rigormortis mostly likely to develop

simultaneously in all muscles.smaller muscles>larger.

Involuntary muscles(myocardium=½hr)>Voluntary muscles>

Eyelids>Neck>Lower Jaw>Face>Chest>Upper Limb>

Abdomen>Lower Limbs>Fingers and Toes.

RM disappears in same order of appearance.

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Rule of 12:

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Development of Rigormortis:

RM is independent of the integrity of nervous system,

concerned only with muscles.

RM occurs in different times with different types of

muscles.(red muscles and white muscles)

Frequent handling of the body breaks rigor in certain

places leaving a patchy distribution.

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Features Observed During Rigormortis:

Pupils are constricted due to Rigormortis of the muscles

of Iris.

CUTIS ANSERINA or goose skin appearance due to

Rigormortis of erector pilae muscle.

Post mortem ejaculations of the seminal fluid in males.

Rarely,if the uterus is in labour at the time of death,the

RM may cause the uterus to contract and expel the foetus.

In Heart,contracted stiff Left Ventricle may be mistaken

for LV HYPERTROPHY.

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Time Of Onset:

Time Factor is VARIABLE,beacause of many extrinsic and

intrinsic factors.

When Rigor sets in early,it passes off quickly and vice versa.

In India ,usually it lasts for 24 to 48 hours in WINTER and

18 to 36 hours in SUMMER.It may begin to disappear in

about 12 hrs.

Rule of FIVE:In some states like kerala( moisture),RM sets

in 5hrs - stays for 5hrs –disappears in 5hrs.

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Conditions Altering the Onset and Duration:

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Conditions Altering the Onset and Duration:Age:

•RM does not occur in a foetus less than 7 months.

•commonly found in stillborn infants at full term,

but it is earlier to appear and also to disappear, so

it has no value as a sign of live birth.

•children & old people:feeble and rapid

Nature Of Death:

1)Diseases causing great exhaustion and wasting(cholera,

typhoid,tuberculosis,cancer, etc) and Violent Deaths(cut

-throat,electrocution,firearms,lightiningStrychnine poisoning)

-»RM EARLY ONSET AND SHORT DURATION.

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Nature Of Death (contd,)

2)POISONING:

• OP poisoning-»rigidity appears early

• CO poisoning-»delays disappearance

• Strychnine and HCN poisoning»»starts early and persists

longer.

3) Asphyxia,severe haemorrhage,apoplexy,pneumonia and

nervous disease causing muscle paralysis -»onset delayed.

4)Widespread bacterial infection, gas gangrene-»

disappear Very rapidly.

*RIGOR MORTIS is frequently absent in septicaemia

deaths.

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Conditions Altering the Onset and

Duration:(contd.)

MUSCULAR STATE:

• Healthy muscles and at rest before Death:slow onset &long

duration of RM.

• Heavy exercise ,Severe Convulsions:Rapid onset and short

duration of RM.

•In a Person who run prior to death,rigor may develop earlier

and rapid in legs,compared to other parts.

•In Emaciated persons:Rigor may be very weak or delayed.

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Conditions Altering the Onset and

Duration:(contd.)

ATMOSPHERIC CONDITIONS:

Cold Weather--->slow onset and long duration.

Rigor persists longer in colder wet air ˃fresh dry air.

prolonged by dry cold air and cold water.

Hot environment:Rapid onset and shorter duration due

to increased breakdown ATP.

Because of the number variability of the factors which

influence the development of RM,it is not possible to

draw any general rule for rate of onset, duration and

disappearance.

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Conditions SIMULATING Rigor mortis:

1)Heat Stiffening:

Exposure of a Body to intense temperature(>65ºC)

Denaturation&Coagulation of muscular proteins

Muscular shortening(contracted,dessicated,carbonised)

Seen in burning,high voltage electrocution,falling into

hot liquid.

A zone of brownish pink “cooked meat” is seen under

contracted muscle.

Changes in posture,especially flexion of limbs

Normal rigor mortis do not occur.

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Conditions SIMULATING Rigor mortis:(contd)

2)Cold Stiffening:

Exposure of a Body to extreme cold(<-5ºC)

Solidification of subcutaneous fat and muscles,

freezing of synovial fluid in joints.

Rigor mortis is halted until thawing occurs,after which

it develops very rapidly and passes off quickly.

When joints forcibly flexed->sudden sharp sound d/t

ice breakage in synovial fluid.

Subcutaneous fat hardening may be mistaken for

ligature mark,especially in infants.

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Conditions SIMULATING Rigor mortis:(contd)3)Cadaveric spasm:

Also known as Instantaneous rigor,cataleptic rigidity or

instantaneous rigidity.

Rare form of muscular rigidity that occurs at the moment of

the death,persists into the period of Rigor mortis and can be

mistaken for RM.

The cause is unknown,but usually a/w violent deaths

happening with intense emotion(possibly neurogenic),

adrenocortical exhaustion(impairing resynthesis of ATP)

No other condition simulates CS and it cannot be produced

by any method after death.

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3)Cadaveric spasm:(contd,)

May affect all muscles in the body,but typically only groups

such as-forearms/hands

Seen in cases of cases of drowning victims when grass ,weeds

roots or other materials are clutched and provides proof of

life at the time of entry into the water.

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3)Cadaveric spasm:(contd,)

Often demonstrates the last activity one did prior to death

and therefore significant in forensic investigations..eg.clinging

on a knife tightly.

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RIGOR MORTIS Vs. CADAVERIC SPASM

RIGOR MORTIS

• Muscle stiffening not marked

• Molecular Death occurs

• BODY heat –Cold

• Muscles do not respond to

Electrical stimuli

• Muscular Reaction-ACIDIC

• MLI:Indicates time of death

CADAVERIC SPASM

• Muscle stiffening MARKED

• Does not occur

• BODY heat-Warm

• Muscles respond.

• ALKALINE

• MODE of DEATH-i,e,homicide/suicide/accident40

Testing RIGOR MORTIS:

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Tested by trying to lift

eyelids

Depressing jaws

Gently bending the

Neck

Try flexing/extending

various joints of body.

Degree->absent/minimal/moderate/advanced/complete.

Distribution->patchy/complete

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Medico legal Importance:Rigor mortis

1) It is a sign Of Death

2) Its extent helps in estimating the time of death.

3)It indicates the position of body at the time of Death.

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TIME OF DEATH

Best done at scene,sooner the better.

Worst estimate is done at the time of autopsy.

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KEY QUESTIONS;

?When was person last seen alive?

?When was body found dead?

DISCUSSION

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THANK YOU

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References:

THE ESSENTIALS OF FORENSIC MEDICINE AND

TOXICOLOGY by K.S.NARAYAN REDDY.

TEXT BOOK OF FORENSIC MEDICINE BY KRISHNAN

VIJ.

BERNARD KNIGHTS FORENSIC PATHOLOGY.

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Appendix

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Appendix