WOUND PRODUCTION

REQUIREMENTS:

1)Force 2)Body / tissue3)Weapon / object4) Contact between weapon & body tissue &

transfer of energy due to impact

MECHANISM OF WOUND PRODUCTION

Force / Energy required for production of a wound is transferred to the tissue as a result of impact between propelling force and counter force.

PROPELLING FORCE:

Movement of object / weaponMovement of the body Combination of above

COUNTER FORCE: Inertia of the body Object against which body

strikes

Energy transmitted to the body as a result of impact is used in:

1. Causing the body to move as a whole2. Causing the non-uniform motion of the

localized tissues. | Compression strains Traction strains

Displacement &deformation in shape

Traction strains FRACTURES/RUPTURES

IMPORTANTRate of transfer of energyDefine the extent of wound

(“It is per unit transfer of energy /unit area/sec”)

FACTORS GOVERNING THE EXTENT AND NATURE OF WOUND

1) Amount of energy discharged during impact

2) Nature of the object causing wound / Weapon Type of weaponMechanical Force (Direct & Indirect)

3) Weight & velocity of weapon (1/2 mv2)

4) Architecture of tissue5) Resistance of the tissue6) Movement of the part struck 7) Time period over which energy is

discharged

BRUISE

BRUISE OR CONTUSION

“It is an extravasation of blood into the tissue due to application of blunt force”.

Damage may not be so evident macroscopically but may be appreciated microscopically.

Mechanism of Production:Sudden pressure to the tissue

due to impact.

Clinical Manifestations:● Pain ● Redness ● Swelling● Epidermis may not show any damage.

APPEARANCE: Shape may or may not correspond the

shape of the weapon.

FACTORS CONTROLLING APPEARANCE OF BRUISE

A) Type of Tissue:More lax tissue- easier for blood to spread- extravasations may move along tissue line (Between muscle bundles) under gravity influence (GRAVITY SHIFTING).

B) Color of Skin:Visibility is better/clear in fair persons.

C) Age:Children and aged bruise easily.

D) Natural Diseases:Coagulation factor’s deficiencies – disease of blood vessels – diminished platelets.

E) Vascularity of the Part: Bruising directly proportional to

Vascularity.

F) Sex:Female especially obese bruise easily.

MEDICOLEGAL IMPORTANCE OF BRUISE

1) It is evidence of application of blunt force.2)Helps in identification of weapon.3) Indicates degree of violence.4)Tells time of infliction of injury.

ESTIMATION OF AGE OF BRUISE

There are two methods

i.From colour changes Due to action of tissue enzyme on the

extravasated blood.

ii. Histologically

COLOUR CHANGES

Fresh: is “RED” – due to oxygenated Hb.After 12 hours: “BLUE” due to deoxygenated

Hb.1-2 days: “BLACKISH BLUE OR BROWN”- due

to Haemosiderin.After 3 days: “GREENISH” due to

Haemotoidin.After 7 days: “YELLOWISH” due to Bilirubin.After 2 weeks: Complete disappearance.

More is the depth & severity of the bruise longer is the time of complete disappearance.

Multiple Bruises

Bruise

ABRASION These are superficial injuries involving

onlyouter layer of skin and do not penetrate

the fullthickness of skin.

Mechanism of Production:Pressure & movement over the skin with

a hardobject.This mechanics results into:1. Moving Abrasion 2. Friction

Abrasion 3. Imprint Abrasion

MOVING ABRASIONS

Gives evidence of direction by pile-up or heaping of epidermis at the far end.

Types A). Scratch B). Graze

SCRATCH

It is due to pointed object passing across the skin, moving the surface layer in front of it. It causes heaping up of epithelium & indicates the direction of force. It also indicates the object which has caused it e.g. marks of the finger nail are Crescentic.

Scratch

Multiple Scratches

GRAZE

It is variation of scratch when a rough object comes incontact with a wider surface of skin usually seen in road side accident.

Graze

FRICTION ABRASION

It is caused by pressure upon the skin accompanied by movement e.g. Ligature mark by a rope in hanging or strangulation and lashes with a whip.

Friction Abrasion

IMPRINT ABRASION

Also called “Patterned Abrasion” In this abrasion pattern of impacting object is stamped on the body when the force is applied at or near at a right angle to the skin surface e.g. when motor tyre passes over the skin or there is impact of design of motor vehicle radiator on the skin.

Imprint Abrasion

AGE OF ABRASION

Fresh Abrasion: is bright in color lymph or blood is oozing.

Scab Formation: Occur within 24 hoursReddish Brown: Within 2-3 daysShedding of the scab and re-epithelization: Within one weekComplete Healing: Within two weeks.

MEDICO LEGAL IMPORTANC

1)May indicate severe internal injury.2)Gives nature of object causing it.3)Tells direction of force.4)Gives timing of injury.5) Indicates manner of infliction.

LACERATION

It is a tear or breach in the tissue caused by a blunt force e.g. Blows from blunt objects, falls or impact from vehicles.

Mechanisms of Production:1) Crushing of tissues between two hard

objects.2) Over stretching of tissue.3) Grinding compression by weight.

TYPES OF LACERATION

Split Laceration : Produced due to sudden compression between two hard objects i.e. weapon & underlying bone on areas like scalp, chin, eyebrow etc.

Split Lacerations

FEATURES1) Breach of tissue.2) External haemorrhage minimal. 3) Bruising of the edges and

surrounding tissue.4) Elements such as hair or

denudation of hair present in the wound.

5) Crushing of hair bulbs

STRETCH LACERATIONBreach of the skin is due to over

stretching slightly away from the point of contract – more seen in industry/vehicular accidents when parts of the body get trapped or when a bone is bent and broken and there is traction strain over skin.

STRETCH LACERATION

FEATURES

1) Breach of skin / soft tissue.2) External haemorrhage.3) Irregular edges.4) Flapping of skin in the direction of stretch.5) Bruising at the point of pressure, not

edges.

LACERATION BECAUSE OF GRINDING COMPRESSION BY

WEIGHTLocalized pressure by heavy

weight causes tear and separation of the skin from underlying tissues – underlying tissue is crushed / minced e.g. passing a vehicular wheel over a limb.

LACERATION BECAUSE OF GRINDING COMPRESSION BY

WEIGHT (Avulsion)

FEATURES

Incomplete tear.Extreme extravasation of blood into

potential spaces of crushed tissue.Less external haemorrhage. Raising of the area above the surface. Tension and pain.

TEAR

It is a type of over stretching by an irregular penetrating object e.g. protruding hinge or door handle of a car.

CUT LACERATIONOR

CHOP INJURIES

By heavy edged weapon such as chopper or hatchet.

FEATURES

1)Breach 2)Bruised edges3)Hair forced in4)Under lying bone usually cut