Forensics Quiz 3

mechanical trauma

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

factors of severity seen in blunt force trauma wounds

• amount of force delivered to the body

• time over which force is delivered

• area of body struck

• amount of surface area of body struck

• nature of weapon or device used to deliver force

abraisions

removal of the superficial epithelial layer of the skin (epidermis) by friction against a rough surface or destruction of the same layer by compression

contusions

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

lacerations

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

fractures of the skeletal system

caused by when a force acts on a long bone, can be caused by direct or indirect application of force

direct force fractures

penetrating, focal, or crush

indirect force

traction, angulation, rotational, vertical compression

stab wounds

depth of wound exceeds length in the skin, length of wound can be less than, equal to or greater than width of the knife, appearance 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

length exceeds depth, clean-cut straight edges from 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 (axe, machete)

therapeutic/diagnostic wounds

created in the conduction of medical care e.g. surgical incisions, surgical stabs for placement of tubes and drains

defensive wounds

usually along the palms of hands, back of the forearms and arms; and on the ulnar aspect of forearm and is sustained trying to ward off attacker

venus air embolism (VAE)

air enters the venous system and travels to the lungs, potentially blocking blood flow and causing severe complications. It is often a complication of medical procedures 

• Penetrating wound of neck or upper chest

• Neurosurgical procedures

• Central venal catheter placement

• Vaginal air insufflation

• Dental procedures

asphyxia

Lack of oxygen in the blood resulting in failure of cells to utilize oxygen and failure of the body to eliminate CO₂. Greek origin meaning breathlessness. Autopsy findings consist of broken/contused hyoid bone, congested face, cyanosis, petechial hemorrhages

smothering

mechanical obstruction or occlusion of external airways (nose and mouth)

suffocation

reduction of oxygen in inhaled air (most commonly replacing oxygen with other cases)

choking

blockage of trachea due to foreign bodies or acute inflammation

autoerotic asphyxiation

intentially induced hypoxia to enhance orgasm

petechial hemorrhage

Rupture of small venules due to rise in venous pressure. Less pressure for jugular veins and more for carotid arteries. Neither specific or sensitive

traumatic asphyxia

restriction of respiratory movements and preventing inspiration (burial in earth after collapse of excavation)

positional asphyxia

person’s position leads to mechanical obstruction of respiration

neck dissection

Used for strangulation cases where all organs are removed including the brain and then layer by layer the trap muscles are dissected and the thyroid gland is examined with the hyoid bone

fire related deaths

presence of burns, gas inhalation i.e. CO poisoning

hyperthermia

Not a lot of findings, but scene investigation is the most important, higher metabolic rate

hypothermia

see vasoconstriction, increased cellular metabolism, shivering, wischnewski spots on the stomach

electrocution

scene investigation is the most important, point of contact burns or electrical marks, may be absent when in the bath, blisters in tissue from passage of current through tissue fluids

drowning

non-specific findings, frothy fluid in mouth and nostrils, lung edema, fluid in stomach, hemorrhages in petrous temporal bones

inhalation of noxious gases

most common cause of fire-related death

first degree burns

erythema and blistering

second degree burns

destruction of full thickness of skin and blistering

third degree burns

destruction of deeper tissue

moist heat injury

water, oil, steam causing burns

dry heat injury

radiant heat causing injury

carbon monoxide blocking oxygen

CO forms from incomplete combustion of hydrocarbons during fire and is inhaled if someone is alive in fire. It binds to hemoglobin molecule with affinity 200-250 times more than oxygen forming COHb which impairs release of oxygen from tissues. Normal level is less than 6% in chronic smokers levels can be 10-15%. Younger or sick are affected by lower levels and can cause death.

physical abuse

contusions, lacerations, and fractures that result from willful acts that were inflicted to cause pain and/or injury and includes inappropriate use of restraints

neglect

contractures (abnormal often permanent condition characterized by flexion and fixation of a limb at a joint), malnutrition, dehydration, decubitus ulcers

decubitus ulcers

These are pressure sores where the most common cause is pressure, usually over bony prominences in an individual with altered consciousness or impaired motor ability. Can also be malnutrition including obesity or moisture. Most common sites are the sacrum and greater tronchanters (hips).

dog bites

bite/claw wounds on the body

snake bites

fang marks, swelling and dicoloration of widespread tissue necrosis

spider bites

mostly not fatal

in-custody deaths

Law enforcement, correctional institutes, mental health facility, or similar institutions has three phases of pre-custody, pre-incarceration (arrest), and incarceration phase

excited delirium

Acute transient disturbance in consciousness and cognition that could possibly be caused by heat stroke, dementia, or high fever. 

Signs can also be violent behavior, abnormally high pain tolerance, superhuman strength, rapid breathing, naked or inappropriately dressed, sweating profusely, hot to the touch, elevated body temperature. 

Possible causes include stimulant drug intoxication, psychiatric disease, metabolic disorders, cessation of struggling is an ominous event.

Autopsy findings: minor abraisions and contusions from the struggle, no significant findings to result in death, and toxicology is positive in cases due to drug intoxication. 

Cause and manner of death can vary. If investigation/autopsy reveals no evidence of asphyxia or causative medical or traumatic condition, then it can be certified as excited delirium syndrome. If there is any evidence on the contrary, then it is a homicide.