Final Exam Flashcards
Antemortem
trauma that occurs before death, there is visible healing
Perimortem
event that occurs at or around the time of death because of the properties of bone, the timing of the injury is less precise when evaluating bone than when evaluating soft tissue. 1. a lack of healing or infectious response 2. the presence of fresh bone fracture characteristics 3. the absence of dry bone fracture characteristics
Postmortem
injuries occurring after death
What is blunt force trauma?
is produced by low velocity impact from a blnt object the low velocity impact of a body with a blunt surface
Key features of BTF?
- Bone that exhibits plastic deformation indicative of low velocity impact
- delamination of bone
- fracture patterns indicating a low velocity site
- location and characteristics of known clinical fracture
- tools or marks or tool impression indicating impact site
- beveling of concentric fractures
BFT intrinsic factors(5)
Bone geometry, bone thickness, bone density, buttresses and struts
Plastic deformation
bending of the bone with permanent deformation
elastic deformation
resilient bending of the bone
fracture
bone failure
Butterfly fractures
failure occurs first on the tension site which on the opposite side of impact * in longbones fractures are initiated on the tension side
classification of forces: Compression
squeezing of the bone along the axis, involved in falls
classification of forces: Tension
pulling apart of the bone
classification of forces: Rotation
twisting of the bone, one end held stationary while the other end twists
classification of forces: Shear
tissue tears apart by sliding one portion
classification of forces: Bending
bone subjected to compression to concave side
Cranial fracture initiation theory
fracture initiate away from point of impact and propagate back towards the point of impact (E.S Gurdjian)
outbending
where fractures initiate because this is where the tension is
BFT extrinsic factors
- shape, weight and material of implement
- rates and duration of loading at impact site
- energy of blow
classification of fracture: Incomplete
doesn’t separate fully, greenstick, depressed
classification of fracture: Complete
bone breaks into 2 or more pieces, transverse, spiral, comminuted, butterfly
classification of fracture: Cranial
linear, diastatic(separation/ fracture/widening of suture) depressed( caving in of vault), stellate( impact and radiating fractures)
GSW: entrance
generally smaller than exit wound and does not have beveling
types of beveling: Outward
seen in the exit wounds, in GSW to the head is on the ectocranial surface
types of beveling: Reverse
is the opposite if what you would expect= is fairly typical in tangential GSW
Steps to GSW (5)
- Entrance
- Radiating fractures
- concentric heaving fractures
- radiating fractures reach opposite side
- Exit
Radiating fracture
are the primary means of relieving stress induced by the impact, length or magnitude is correlated with the relative power of the weapon
Concentric fracture
produced after radiating fractures, are seen as a series of independent arcs between radial fractures sharing similar radii, produced due to intercranial pressure
caliber
the size of projectile or weapon barrel (diameter)
gauge
the barrel diameter of a shot gun
pellets
solid balls of lead (size either buck or bird)
bullet profile
sharp= rifles
blunt= handgun
hollow point= handgun
bullet jacketing
thin metal covering (full, semi, or lack of jacket)
velocity
the variable that has the greatest effect on wounding power( rifles are high velocity, hand and shot are not)
wound shapes
round, oval, keyhole, irregular
4 factors: wound shape
- bullet construction
- angle of trajectory
- angle of bullet axis
- entry or exit
determining distance of fire
forensic pathologists job, analysis of skin, presence of soot, tattooing, conditions of remains can affect ability to determine
keyhole defect
when bullet enters on an angle and causes a bit if external beveling (tangential defect)
submandibular or intraoral GSW
The blast injects gases and pressure, the skull fractures depending of the trajectory skull can fractures symmetrically fashion.
factors that influence entrance wound
- loss of gyroscopic stability= irregular wound
- intermediate targets(skin, clothing…)
- tangential impacts= create irregular morphologies and a larger entrance than bullet
- exiting fractures
- variations in shape, surface, and strength of bullets
Bone repair
- hematoma/ inflammation= 1 week
- soft callus= 2-3 weeks
- hard callus(bone starts to form)= 4-16 weeks
- remodeling= 17+ weeks
forensic taphonomy
is the study of the processes that affect animals and plant remains as the become fossilized “forensic” is a subfield of forensic anthro that examines hoe taphonomic forces have altered evidence
Wendy C.
skull superimposition, rib fractures both perimortem and antimortem
Alt. strategy: osteogenisis
(bio profile) nature of injury, nature of treatment, time between injury and death
Alt. strategy: the death event
(perimortem period) manner of death, cause f death, skeletal evidence, context may be important
Alt. strategy: disposition of remains
(anthropogenic context) haphazard, burial, burning, water environment, surface(dismemberment)
Alt. strategy: taphonomy
natural taphonomic evidence: animals, weathering, plants, aqueous effect, staining
Randy Laufer case
John McCrae police, 15 year old male buried outside house, positive id by dental xrays, was said to be a trophy skull
4 steps in autopsy after GSW
- history
- xray
- external
- internal
range of fire: near contact/ close range
mussle not in contact with skin no powder tattooing
range of fire: intermediate
powder tattooing= unburned powder embedded in dermis of skin just like tattoo
range of fire: distant
no soot, no tattooing, searing or carbon monoxide
Predict Pediatric Skull Fracture Pattern IMPETUS for STUDY
- human pediatric cranial trauma cases
- inflicted vs. accidental
- lack of baseline data
- gap in best practice
Predict Pediatric Skull Fracture Pattern: research objectives
- document cranial vault fx on infant porciine specimen with respect to energy, age and impact of interface
- identify fx characteristics of developing porcine skull under known conditions
Predict Pediatric Skull Fracture Pattern: Top 5 Points
- with high erg comes high fx initiation and propagation
- fx occur at similar locations across individuals of a given age and interface
- fracture initiation occurs away from impact, propagates back towards impact, initiation at bone suture, diastatic fracture present near crack tip
- fracture patterns from rigid and compliant interface
- multiple fx are consistently produced from a single impact
Predict Pediatric Skull Fracture Pattern: implications of the findings
clearly one blunt force impact can produce multiple cranial fx
types of identification: tentative
the id of the decedent is suspected based on circumstances or associated materials such as wallet/ drivers license
types of identification: presumptive
meets high standard than tentative but lesser than positive, circumstances or general characteristics provide investigators with a basis for id and there is no exclusionary evidence
types of identification: positive
id proves beyond reasonable professional doubt that a set of am and pm medical records belong to the same individual
Methods to positive id
fingerprints, nuclear DNA, comparative radiography(dental or medical)
method of positive id used by forensic anthro
- construct bio. profile
- submit bio profile to law enforcement
- law enforcement identifies potential missing people
- am radiographs submitted
- pm xrays taken
- am and pm compared
medical radiography
compare: trabecular patterns, radiopacity(light spots), radiolucency(dark spots), anomalies and pathologies, post surgeries
dental radiography
- peripapicals- upper or lower teeth with roots
- bitewings- focus on crown
- panograms- full mouth shot
- dental restorations- amalgam fillings, composite restorations, crowns, root canals
- pulp chamber, spatial relationships between teeth
Categories of Forensic Art: composite imagery
graphic images made up from the combination of individually described component parts (tattoos, sketches, surveillance images)
Categories of Forensic Art: image modification and id
methods of manipulation, enhancement, comparison and categorization of photograph (age progression, fugitive cases, photo manipulation, age regression)
Categories of Forensic Art: demonstrative evidence
any artwork that applies to a courtroom
Categories of Forensic Art: reconstruction and postmortem id aids
methods to aid in the id of human physical remains in various conditions( postmortem drawings soft skin included, 2D and 3D skull drawings)
3D facial reconstruction
depth markers placed anthropologically to indicate the persons soft tissue
Why should bone be tested for DNA?
individual id, familial id, ethnic id, species id, determination of sex, disease that manifest in bone
Nuclear DNA
2 copies/cell, inherited from both parents, unique to individual
mtDNA
less than 1000 copies/cell, maternally inherited, not unique to individual
Breakdown of Bone DNA
what affects taphonomy: bone size, bone density, organic vs. non organic, moisture/temperate, ph, critters, mechanical means
bone extrinsic factors
object shape, weight, loading rate, loading duration
