different types of injuries and wounds - forensic pathology

Mechanical Trauma

occurs when the force applied to skin or bone exceeds the mechanical or tensile strength of the tissue

Factors in determining the severity, extent and appearance of blunt force injuries

1. Amount of force delivered to body

2. Time over which force delivered

3. Area of body struck

4. Amount of surface area of body struck

5. Nature of weapon or device used to deliver force

Four categories of injuries

1. Abrasions

2. Contusions

3. Lacerations

4. Fractures of the skeletal system

Abrasions

Injury to the skin in which there is removal of the superficial epithelial layer of the skin (epidermis) by friction against a rough surface or destruction of the same layer by compression

Three types of abrasion

1. Scrape or brush abrasion

2. Impact abrasion

3. Patterned abrasion

Scrape or brush abrasion

leaves denuded surface, “road rash”

Impact abrasion

force directed perpendicular to surface, crushing it, over boney prominences

Patterned abrasion

version of impact; imprint of object or intervening material

Bite Marks

• Actual injury rare

• Patterned abrasion with underlying hemorrhages

• Often sexual in nature

• Can be compared with suspect’s dentition

Contusions (Bruise)

Area of hemorrhage into soft tissue due to rupture of blood vessels caused by blunt trauma

Where can we find Contusions

can be present only in skin or also seen in internal organ

Factors influencing the side of the contusion

age, sex, condition and health of individual, site and tissue struck

Contusions: Aging

Rough Estimate

Aging of bruises

• color changes from blue-red to dark purple to green to yellow to brown

• The change of color may be used as a guide for aging the injury

Lacerations

A tear in the tissue caused by either a shearing or crushing force

Fractures

caused by when a force acts on a long bone

Fractures can be caused by

direct or indirect application of force

Direct force fractures:

Penetrating, focal, or crush

Indirect force fractures:

traction, angulation, rotational, vertical compression, angulation and compression

Internal Organ Injuries

• Ribs

• Heart

• Aorta

• Solid abdominal organs

• bladder

Ribs

pathologic, iatrogenic, direct localized violence and indirect violence

Heart

Commotio Cordis

Aorta

Lacerations of thoracic aorta occurs distal to origin of the left subclavian artery, ascending lacerations from increased pressure.

Solid abdominal organs

parenchymal lacerations urinary

bladder

rupture

Sharp Force wounds

wounds caused by pointed and sharped edge devices

Categories of sharp force wounds

1. Stab wounds-depth of wound exceeds length in the skin

2. Incised wounds-length of wound exceeds depth

3. Chop wounds

4. Therapeutic diagnostic wounds

Stab wounds characteristics

appearance of wound depends on nature of blade and knife; direction of force; movement of blade in wound; movement of victim; and state of the skin

Incised Wounds

wounds produced by sharp-edged devices, wherein the length is greater than the depth

Incised wounds characteristics

• clean-cut straight edges free of abrasion or contusion

• no bridging of soft tissue in the wound

• usually not fatal; seen more in suicides than homicides

Chop Wounds

wounds produced by heavy devices with cutting edge (axes, machete)

Defensive wounds

special consideration for these wounds, usually along palms of hands, back of the forearms and arms and on the ulnar aspect of forearm

Venous Air Embolism

• Penetrating wound of neck or upper chest

• neurosurgical procedures

• central venous catheter placement

• vaginal air insufflation

• dental procedures

Therapeutic/ Diagnostic Wounds

Created in the conduction of medical care

Manner of Death

How the death came about (circumstances)

Natural

disease process

Accident

injury with no volitional act to harm

Suicide

injury from volitional act to harm oneself

Homicide

injury from volitional act to harm another

Undetermined

body not recovered/ inadequate info

Mechanism of injury (MOI)

how the injury was created

MOI can be:

• Firearm

• Knife

• Blunt object

• Vehicle

• Drug

Cause of Death (COD)

The disease or injury that leads to death

Disease

categories can be named by system (e.g. cardiovascular, respiratory, central nervous)

Injury

categories include gunshot wounds, blunt force injuries, sharp force injuries, electrocution, etc.

Firearm

Gun shot wound to the head

Knife

Stab wounds

Vehicle

Multiple traumatic injuries

Fall

Blunt force injury of the pelvis

Drug

Toxicity

Water

Drowning

Noose

Hanging

Mechanism of Death (MOD)

The physiological derangement produced by the cause of death that results in the death

Multiple CODs

can produce a single MOD

A singe COD

can produce multiple different MODs.

Types of small arms

• Handguns

• Rifles

• Submachine guns (machine pistols)

• Machine guns

• Shotguns

Handguns

• Single-shot pistols

• Derringers

• Revolvers

• Auto-loading pistols (automatics)

Rifles

Firearm with rifled barrel designed to be fired from the shoulder

What are Rifles

Single-shot, lever-action, bolt-action, pump-action and auto-loading

Submachine Gun

Firearm designed to be fired from the shoulder and/or hip

Machine gun

crew or single individual operated, majority have ammunition fed by belts

Caliber

Rifled weapons have spiral grooves cut the length of the bore of the barrel

Shotguns

Firearm designed to be fired from the shoulder

Gauge

Describes the caliber of a shotgun

Choke

described the partial constriction of the barrel at the muzzle to reduce pellet spread

Ammunition

• cartridge case

• primer

• propellant (gunpowder)

• bullet or projectile

Discharge of a weapon 1.

Pulling trigger releases firing pin

Discharge of a weapon 2.

Firing pin strikes primer igniting primer composition producing large flame

Discharge of a weapon 3.

Flame ignites powder producing gas and heat

Discharge of a weapon 4.

Gas produces pressure on base of bullet and sides of case

Discharge of a weapon 5.

Pressure of gas propels bullet down barrel

Discharge of a weapon 6.

Some gases leaks past bullet; majority of gas and unburnt powder emerge after the bullet

Characteristics of surface wounds

• entrence versus exit

• distance of weapon: Contact, close and distant

Issues with GSW

• Structures injured

• Trajectory of bullet path in body

• Retained bullet/ bullet fragments

• Number of gunshot wounds

Range of discharge

• Contact and near contact

• Intermediate

• Distance or indeterminate

Entrance wound

Inward bevel

Exit wound

Outward bevel

Severity of the gunshot wound determined by two factors

• Disruption of the tissue caused by the mechanical interaction between the bullet and the tissue

• The effects of the temporary cavity

Explosive

Substance that undergoes a rapid chemical reaction that transforms a liquid or solid into a gas releasing energy

Low-order explosive:

Deflagration; subsonic speeds

High-order explosives :

Pressurized gas at supersonic speeds

High order:

• Shock/Blast wave

• Blast Wind

Primary Blast Injury:

• Direct result of impact of the blast wave upon the body

• Rupture of tympanic membranes

• Abdominal injuries

• Blast lung injury

• Amputations

• Body fragmentation

Secondary blast injuries

result from flying debris (rocks, glass, wood) and bomb fragments energized by the explosion

Trauma from Secondary blast injury

• Penetrating trauma

• Blunt force trauma

Tertiary blast injury

• Result of the body striking on object

• Blunt force trauma

Quaternary blast injury

All explosion-related injuries, illnesses, disease not due to above categories

Injuries from Quaternary blast injury

• Thermal and chemical burns

• Inhalation injury

• Radiation exposure

• Exacerbation of chronic disease

Severity of injury due to firearm depends

primarily on disruption of tissue from bullet and temporary cavity

Injuries from blasts depend on

type of blast, distance from blast and intermediary structures