Mechanical injury 1

MECHANICAL INJURIES

TRAUMATOLOGY.The branch of forensic

medicine which deals with the study of trauma and its effect on human body is called TRAUMATOLOGY.

Important terms

TRAUMA– Insult to living tissues– It applies as well as to emotional or

mental stress.

Important terms Injury: (Sec. 44 PPC)

– Any harm whatever illegally caused to a person in body, mind, reputation or property. 

Hurt: (Sec. 332 PPC) – “Whoever causes pain, harm, disease,

infirmity or injury to any person or impairs, disables or dismembers any organ of the body or part of any person, without causing his death is said to cause Hurt”

Important terms Wounds:

– A disruption of the normal structure of tissues caused by the application of force to the body.

Battery:– “It is the actual application of unlawful

force to another” directly or indirectly.

CLASSIFICATION OF INJURIESON BASIS OF WEAPON USED

1.Injuries caused by blunt weapon– a. Bruise.– b. Abrasion include scratch, graze ,

imprint.– c. Laceration include evulsions , stretch,

split.   2.Injuries caused by sharp weapon

– a. Incised wound( cuts).– b. Stab wounds ( puncture).

3. Injuries caused by fire arms.– a. smooth board weapon( shot gun injury).– b. Rifled weapon include low & high

velocity.

CLASSIFICATION OF INJURIESON BASIS OF WEAPON USED

4. Thermal injuries ( injuries caused by heat & cold).

5. Corrosive injuries– a. Acid. b. Alkalies.

 6. Electricity.– a. Low voltage. b. High voltage.

7.Radiation injuries.– a. Natural.– b. Artificial.

4. Thermal injuries1. Produced due to cold a. local hypothermia b. Frost bite c. Trench foot d. immersion foot e. General hypothermia.2. Produced due to heat. a. burns b. scalds c. produced by gen. application of heat.

( heat stroke, heat exhaustion, heat crams )

 CLASSIFICATION OF INJURIESON BASIS OF Mechanics & Manner of infliction

ON BASIS OF MECHANICS OF WOUND PRODUCTION– 1. Injuries caused to stationary subjects.– 2. Injuries caused to moving subjects.

ON BASIS OF MANNER OF INFLICTION.– 1.Suicidal/ self inflicted.– 2.Homicidal.– 3. Accidental.

CLASSIFICATION OF INJURIESON BASIS OF Time of infliction & type of energy

DEPENDING UPON TIME OF INFLICTION– 1. Ante mortem.– 2.Postmortem.

DEPENDING UPON TYPE OF ENERGY– 1.Mechanical injuries.– 2. Chemical injuries.– 3. Electrical injuries.– 4. Thermal injuries.– 5. Radiation injuries.

LEGAL CLASSIFICATION

QISAS AND DIYYAT ORDINANCE 1.Itlaf-I- udw.

2.Itlaf-I-salahiyat-I-udw. 3.Shajaah

– a. Shajjah Khafifah. – b. Shajjah Madihah.– c. Shajjah Hashimah.– d. Shajjah Munaqillah.– e. Shajjah Ammah.– f. Shajjah Damighah.

LEGAL CLASSIFICATION

QISAS AND DIYYAT ORDINANCE 4.Jurh.

– Jaifah.– Ghayr Jaifah1. damiyah2. Badihah.3. Mutlahimah.4. Madihah.5. Hashimah.6. Munaqillah.

MECHANISM OF WOUND PRODUCTION

FACTORS AFFECTING APPEARANCE OF WOUND:

1) TYPES OF WEAPON.2) EXECUTION OF MECHANICAL FORCE.3) WEIGHT & VELOCITY OF THE AGENT.4) ARCHITECTURAL DESIGN OF TISSUE.5) RESISTANCE OF TISSUE.6) MOVEMENT OF THE PART STRUCK.

1) TYPES OF WEAPON :

DIRECTLY CONTROL SHAPE OF WOUND

e.g. INJURIES PRODUCED WITH SHARP/ BLUNT/ FIREARM WEAPONS.

2) EXECUTION OF MECHANICAL FORCE: INTERACTION B/W WEAPON & PART.

TWO MANNERS OF APPLICATION OF FORCE.

i) DIRECT APPLICATION OF FORCE: PRODUCES WOUND AT POINT OF APPLICATION. IMPACT INJURIES

e.g.

CLUB/ KICK/ BRICKS. LIGATURE MARKS. TEETH MARKS.

ii) INDIRECT APPLICATION OF FORCE PRODUCES WOUND AWAY FROM SITE OF IMPACT.

e.g. STRETCH LACERATION. DECELARERATION OF CRANIUM

WEIGHT & VELOCITY OF THE AGENT:

DETERMINE THE WOUNDING POWER OF ANY MOVING OBJECT.

K.E = ½ mv2

BRICK CLUB. BULLET. CHIEFLY PROPORTIONATE TO THEIR WEIGHT &

VELOCITY.

ARCHITECTURAL DESIGN : HUMAN BODY composed of DIFFERENT TISSUES SOFT & ELASTIC

e.g. SKIN/ FAT/ MUSCLE/ INTERNAL ORGAN. RIGID & LESS ELASTIC

e.g. LIGAMENT/ CARTILAGE. HARD HAVING LIMITED ELASTICITY e.g. BONE. ELASTICITY OF BONES. AGE OF PERSON & EXTENT OF

CALCIFICATION. INFANTS - ELASTIC. ADULTS / OLD - BRITTLE. - easily break.

SHAPE OF BONE: LONG » LIMBS , RIBS. PLATE LIKE » VAULT OF SKULL/ CREST OF ILIUM. SHORT » BONES OF HANDS/ FEET.

PART OF BODY

COMPACT » LIMBS CAVITY » ABDOMEN/ CHEST/ CRANIUM.

ORGANS OF DIFFERENT SHAPES & CONSISTANCY.

e.g. SOLID » LIVER / SPLEEN / KIDNEY. SPONGY » LUNGS. HOLLOW SACS » STOMACH / INTESTINE/ HEART/ GALL

BLADDER/ URINARY BLADDER.

IMPACT WITH SAME FORCE & SAME DIRECTION ON DIFFERENT PARTS PRODUCE DIFFERENT INJURIES.

e.g. FOREHEAD » LACERATION BUTTOCK » BRUISE.

RESISTANCE OF TISSUE: SOFT & ELASTIC TISSUE ABSORB FORCE. HARD & IN ELASTIC FRACTURED WITH SAME FORCE

EFFECT OF MOVEMENT OF THE PART.

STATIONARY PART OR IN MOTION

STATIONARY HEAD PRODUCES INJURIES AT SITE OF IMPACT MOVING HEAD PRODUCES INJURIES ALSO OPPSITE SITE OF

THE IMPACT.

HEAD INJURIES COUP INJURIES A strike on a stationary head

produces injury of scalp, bone & brain at the site of impact.

CONTRE COUP INJURIES It is produced on the opposite

side of impact.

HEAD INJURIES

TIMING OF WOUNDS

1. NAKED EYE APPEARANCE OF WOUNDS

2. HISTOLAGICAL TIMING OF WOUNDS.

3. HISTOCHEMICAL TIMING OF WOUNDS.

4. BIOCHEMICAL TIMING OF WOUNDS.

Naked Eye appearance of

woundsSome time it is possible to determine the nature of wound, either antemortem or postmortem.

Antemortem wound

Postmortem Wound

1 Bleed freely Bleeding is slight from cut veins

2 Extensive infiltration of deeper tissues

Less infiltration of deeper tissues

3 Edges are gaping Edges are do not gap4 Edges are Everted Not everted5 Firmly coagulated

blood found in and about the wound

Little or no coagulated blood will be found in and about the wound

6 Arterial spurting marks may be found

absent

7 Vital reaction is present

Vital reaction is absent

Histological timing of the Wound

The histological estimation of the age of injuries is based on the morphology of various stages of wound healing.

1. Survival period less then 4 hours after

injury No distinct histological signs of

inflammation. Histological distinction between

antemortem and postmortem wounds is not possible during this period.

2. Survival period 4 to 16 hours.

At 4 hours some neutrophil granulocytes appear pericascularly.

At 8-12 hours, polymorphnuclears, macrophages and activated fibroblast from a distinct peripheral wound zone.

At 12- 16 hours granulocytes dominate macrophages in the ratio of 5:1.

Imminent necrosis in the central wound zone.

3. Survival period 16 to 48 hours.

At 16- 24 hours the relative number of macrophages increases, the ratio of polymorphnuclears to macraphages falling to 0.4.

After 16 hours, older fibrin stains red with Martius scarlet blue, whereas before 16 hours , newer fibrin stains yellow.

At 24 hours number of granulocytes and amount of fibrin increase to maximum.

At 24-48 hours, the epidermis grows from the incised edge forward the centre of the wound.

At 32 hours, necrosis is apparent in the central wound zone.

At 48 hours, macrophages reach their maximum concentration in the peripheral zone.

4. Survival period 2 to 4 days

At 2-4 days, fibroblasts migrate from the nearby connective tissue to the wound periphery.

At 3-4 days, capillary buds appear.

At 4-5 days, epithelialization of small wounds and abrasions is complete.

5.Survival period 4 - 8 days.

At 4 days, first collagen fibres are seen.

At 4-5 days, there is a profuse ingrowth of new capillaries.

At 5-7 days, epidermal thickness decreases to nearly normal.

At 6 days, lymphocytes reach their maximum concentration.

6. Survival period 8 -12 days

At 8-12 days, there is decrease in the number of leucocytes, fibroblasts and capillaries.

There is increase in the number and size of collagen fibres.

7. Survival period over 12 days.

At 12 days, there is definite regression of cellular activity in the epidermis and dermis. The vascularity of dermis diminishes.

Collagen fibers are restored.

HISTOCHEMICAL TIMING OF WOUNDS

IT INVOLVES THE STUDY OF ENZYMES IN THE WOUND REGION.

In antemortem wounds, two distinct zones of enzyme activity are seen.

1. The 100-300 micrometer deep peripheral zone shows increase in enzyme activity is called POSITIVE VITAL REACTION.

2. The 200-500 micrometer deep central zone shows a progressive loss of enzyme activity is called NEGATIVE VITAL REACTION.

Enzymes Time in hour(s)

Adenosine triphosphatases & Estrases

1

Aminopeptidases 2

Acid phosphatases 4

Alkaline phosphatases & polymorphonuclears

8

Mononuclears 16

Biochemical changes It depends upon the measurement

of HISTAMINE and SEROTONIN contents of the injured skin.

Indications that the wound was inflicted before death if : SEROTONIN: The maximum increase occurs

within 10 min and at least 2 fold after injury.

HISTAMINE: The maximum increase occurs

within 20 – 30 min and 1.5 fold after injury.