Death Investigation Exam 2

abrasions, contusions, lacerations, fractures of skeletal system

what are the four types of blunt force trauma

amount of force, time over which force delivered, region struck, extent of body surface, type of weapon, condition of body

what are the six factors affecting the severity, extent, and appearance of blunt force injuries

abrasion

An injury to the skin in which there is removal of the superficial epithelial layer of the skin (the epidermis) due to friction against a rough surface with resultant scraping away of the superficial portions of the epidermis, or destruction of the superficial layers by compression.

scrape/brush abrasion

type of abrasion that scrapes off the superficial layers of skin leaving a denuded surface. It may extend into the dermis causing capillary bleeding and deposition of serosanguineous fluid

road rash

what is a severe example of a scrape/brush abrasion

impact abrasion

type of abrasion where the force is directly perpendicular to the skin, crushing it. Commonly seen over bony prominences and in individuals who collapse and hit their heads on the ground

patterned abrasion

type of abrasion in which an imprint of the offending object is imprinted or stamped on the skin by the crushing effect of the blunt object

insect bites or diaper rash

what may be misinterpreted as an abrasion

scab formation, epithelial regeneration and covering, subepithelial granulation and epithelial hyperplasia, regression of epithelium and granulation tissue

what are the four stages of healing in an abrasion

subepithelial granulation

new connective tissue and capillaries are formed under the surface of the healing skin defect

epithelial hyperplasia

increased cell production in the epithelium

the victim lived after injury

what do scabs indicate

contusion

an area of hemorrhage into soft tissue due to rupture of blood vessels caused by blunt trauma and can also be found in internal organs. May or may not be patterned

hematoma

a large focal collection of blood in an area of contusion

the amount of force applied and the structure and vascularity of the tissue injured

the extent and severity of a contusion depends on what two things

age, sex, condition of victim, site and type of tissue struck

what four factors affect the size of a contusion

skin

what medium is difficult to photograph due to topography

false

t/f: consistent microscopic dating of contusions has been found to be accurate

recent or old

what are the terms used to define bruises

postmortem contusions

contusions that may occur if a severe blow delivered within a few hours of death or from the surgical removal of the corneas or globes of eyes after death

laceration

a tear in the tissue caused by either shearing or a crushing force. Can occur in internal organs as well. Irregular with abraded and contused margins. Most common over bone

avulsive injury

type of laceration where the force impacting the body does so at an oblique or tangential angle to the skin, ripping skin and soft tissue off the bone

penetrating fractures

fracture that is a large force acting on a small area. Ex: gunshot wound

focal fractures

fractures that is a small force applied to a small area Ex: bat

crush fractures

fractures that is a large force applied over a large area Ex:MVA

comminuted fractures

fractures that occur when the bone is broken into more than two pieces

angulation

bone bent until it snaps

250-350

how many autopsies a yr per ME office is recommended

1300

what is the back log in the ME office

depth and detail of shoe, degree and speed of impact, angle of shoe relative to skin, clothing interference, victim movement

what are the five factors affecting quality and detail of footwear impressions on a body

outer edges

blood goes where in blunt force

women

which sex bruises easiest

yellow

what color indicates a bruise is healing

scleral hemorrhaging

what can occur when getting vitreous fluid from the eye

true

t/f: bite marks are blunt force trauma

rotational

bone is twisted and a spiral fracture occurs

vertical compression

oblique fracture of the body of a long bone

MVA

what is the leading cause in brain injuries

impact injuries

injury to the brain caused by an object striking the head

acceleration/deceleration injuries

injury to the brain caused by the sudden movement of the head immediately after injury with resultant production of intracranial pressure gradients and the subjecting of the brain to both shearing and tensile forces

laceration abrasion and contusions of the scalp, skull fracture, brain contusions, epidural hematomas, intracerebral hematomas

what are the five injuries from impact trauma

subdural hematoma

most common lethal injury associated with head traumas

diffuse axonal injury

secondary to injury to the axons

amount of hair, thickness of scalp, thickness of skull, elasticity of bone at impact point, object itself, velocity of blows

six factors affecting the extent of a skull fracture

no correlation

there \______________ between the severity of brain injury and the production of a linear skull fracture,

simple linear fractures

fracture seen in low-velocity impacts with a large area of contact between the head and impacting object Ex: fall to pavement

stellate

increasing velocity and energy of impact will result in what type of fracture with depression of the bone at the point of impact

circular

with increased velocity, one may have a series of complete or incomplete \______________ fractures encircling the impact point

depressed skull fracture

fracture that occurs when the skull is truck with an object having a relatively large amount of kinetic energy but a small surface. Ex: hammer. No linear fractures radiate from this

basilar skull fractures

skull fracture that occurs in the base of the skull and may hinge the skull aka bisect it

coup contusion

brain contusion that occur at the site of impact and are the result of the inbending bone snapping back causing tensile force injuries to the brain. Less common

contrecoup contusion

brain contusion that occurs in the areas of the brain directly opposite to the point of impact due to tensile force injuries by the brain rebounding backward from the skull following impact. Ex: falls

epidural hematomas

what is always a coup injury and never a countrecoup injury and produces a disk shape

subdural hematomas and contrecoup

which pair go together with falls

stab wound

produced by pointed instruments with sharp edges around the wound and without abrasion or contusion.

stab

depth of the wound into body is greater than its length on the skin surface

readily

the sharper, more needle-like the tip of the instrument, the more \_______ it will perforate the skin

weapon, direction of thrust, movement of blade in wound, movement of victim, tension/relaxation, langer's lines

what six factors affect stab wound appearance

langers lines

a pattern of elastic fibers in the dermis of the skin, which is approximately the same from individual to individuals. Perpendicular \= gapping wounds; Parallel\= slit-like wounds

incised wounds

produced by a sharp edged weapon drawn over the skin with sufficient pressure to produce an injury

cut

length of the wound on the body is greater than its depth into the skin surface

greater, lesser, equal

depth of the stab wound can be \______, \______, or \_______ than the length of the blade

hilt mark

bruise by the stab wound caused by a part of the knife handle

ricasso

part of the knife between the handle and the blade

hemopericardium

heart filled with blood

unknown but 320 millionppl and 320mill guns estimated

how many people own a gun in the US

single shot pistol

one firing chamber integral with the barrel and must be loaded manually each time the weapon is fired

derringers

a variant of a single-shot pistol; small pocket firearms having multiple barrels; each barrel can be fired separately

revolvers

until the 1970's, the most common type of handgun. Have a revolving cylinder that contains several chambers each with a single cartridge

swingout, breaktop, solid-frame

what are the three types of revolvers

automatic

firearm designed to feed cartridges, fire them, eject their empty cases and repeat this cycle as long as the trigger is depressed and cartridges remain in the feed system Ex: machine gun

semi automatic

firearm in which each pull of the trigger results in a complete firing cycle, from discharge to reloading. Necessary that the trigger be released and pulled for each cycle. Discharge and chambering of a round is either blowback operated, recoil operated, or gas operated

lands and grooves

what are responsible for providing a projectile with a spiraling motion for accuracy

caliber

the diameter of the bore of rifled small arms designated in the hundredths or thousands of an inch.

penetrating

bullets enters and does not exit

perforating

bullet passes completely through the object

bullet, flame, soot, burned and unburned gunpowder

what comes out of the end of a barrel when a shot is fired

entrance wound

wounds that are round to oval configured with a reddish-brown margin of abraded skin called the abrasion ring

contact wound

when the weapon is held against the surface of the body at the time of discharge

hard contact wound

contact wound in which the muzzle of the weapon is jammed against the skin with lots of force, indenting it (skin envelopes muzzle); wound edges are seared by the hot gases of combustion and blackened by the soot deposition

hands

where is blood spatter found in cases involving self-inflected contact or near contact wounds

loose contact wound

contact wound in which the muzzle is held lightly against the skin; soot carried by gas is deposited in a zone around the entrance; soot can be easily wiped away; a few grains of unburnt gunpowder may also escape and be deposited in this zone

angled contact wound

contact wound in which the barrel of the weapon is held acutely to the skin; complete circumference of the muzzle is not in contact with the skin, gas and soot escape producing an eccentrically arranged pattern

incomplete contact wound

contact wound in which the muzzle is held against the skin, but because the body surface is not flat, there is a gap between the muzzle and the skin; a jet of soot-laden gas escapes producing an area of seared, blackened skin; most often seen in self-inflicted wounds to the head bc of long arms

over bone

type of contact wound that will produce a stellate or cruciform appearance bc of gases from the discharge. When the stretching exceeds the elasticity of the skin, it will tear

near contact wounds

contact wounds that are a gray zone in which the muzzle of the weapon is not in contact with the skin and held a short distance away. The entrance wound is surrounded by a wide zone of soot overlying seared , blackened skin. Soot is baked into the skin and cannot be wiped away and unburned powder can be present

oval; circular

\__________ abrasion rings suggest gunshots fired at an angle, while \________ abrasion rings suggest perpendicular directionality

soot

carbon produced by the combustion of the gunpowder that can contain vaporized metals from the primer, bullet, and cartridge case

range, propellant, angle of muzzle, barrel length, caliber, type of weapon, target material/state of target

size, intensity, and appearance of soot patterns depend on what seven things

increases, decreases

As the distance between the muzzle and the target increases the pattern of particles on the target \________ in diameter and the density of the particle dispersion \_____________

8-12 in

what is the max distance out to which powder soot deposition occurs for most handguns

test firing the gun

what is the only way to determine the range of fire reliably

intermediate range wounds

wounds in which the muzzle of the weapon is held away from the body-yet sufficiently close enough so that powder grains expelled from the muzzle along with the bullet produce powder tattooing of the skin

0.394 in

for handguns, powder tattooing begins at a muzzle-to-target distance of about

stippling

numerous red-brown to orange-red punctate lesions surrounding the wound entrance.

antemortem

is powder tattooing/stippling a antemortem or postmortem phenomenon

powder burns; wiped off

powder tattooing are NOT and cannot be

hands and soles of feet bc rough

where is powder tattooing rare and why

18-24 in

powder tattooing for handguns will extend to a max distance of

distant range gunshot wounds

wounds in which the only marks on the skin are those produced by the mechanical action of the bullet passing through the skin. No soot or powder tattooing present and range determination is not attainable.