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TraumaAmerican Academy of Forensics Sciences Meet every year in various cities across the country Memberships constitutes the top forensic experts from all over the world Judicial system—ME’s, MD’s, jurors Forensic Anthropologists Presentations Board certification exams Antemortem Before death Prosthetics—serial numbers can lead to identification Postmortem After death Animals chewing on bones, weathering (taphonomic processes), etc. Perimortem At or around the time or death Can help investigators evaluate violence against individuals, i.e. force used on individual serious enough to leave evidence on bone Pathologist and Anthropologist Cooperation Correlate skin and soft tissue injury with patterns of skeletal trauma Two major kinds of injury to bone: High velocity (ballistic) Impart their energy so suddenly that bone reacts as brittle matter and shatters Blunt force (sharp instrument also a form of blunt force) Lower energy, bending forces, slower impact deliver a gradual rate of loading Bone reacts more as a “ductile” material capable of showing plastic deformation Ex—basketball **Sharp force injuries (combo) Potentially a blend of characteristics—incised bone combined with blunt force Appearance of Bone Injury Reflects: Shape Area Mass Speed Direction …of instrument applying external force but also… Intrinsic strength of the bone injured Anatomy of that bone Thickness of that bone Mineral content of that bone Overall health of the bone Function of Bone Support weight Anchor muscles against contracting forces Must be light, yet strong, for active movement (if brittle, would shatter) If pliable like rope, would collapse Visio-elastic structure of bone provides adaptive responses to both extremesTraumaHydroxyapatite crystals and calcium salts are unyielding brittle component, and collagen salts are the elastic, yielding, ductile component These two responsible for unique morphology of fractures and defects caused by trauma Trauma usually means: extrinsic forces Extent of damage, amount of energy from impacting object and size of impacted area In general, trauma affects the skeleton in 4 ways: Partial or complete break Abnormal displacement/dislocation Disruption in nerve and/or blood supply An artificially induced, abnormal shape or contour Skull has two tables, outer and inner, and a layer of spongy, or trabecular, bone in between (diploe) like a sandwich Gunshot Wounds Signature patterns Orientation of victim relative to shooter Sequence of wounds Entry and exit characteristics: Bullet enters perpendicular to cranial bone Outside—smooth, round (circular) hole on external table Bullet punches through and creates a ragged, cone-shaped internal bevel on internal table If enough energy, keeps going…external table has beveled look 3 distinct fracture types for gunshot wounds Plug and spall Initial impact, projectile punches through external table to internal table, minimal force may create this Radiating fractures Greater force needed as pressure inside skull increases Heaving concentric Radiating fractures cannot relieve pressure, heaving, con central fractures result to absorb pressure skull Bone Beveling Does Not Lie Radiating fractures will continue expanding until pressure subside or energy is dissipated into an existing fracture or suture Fractures that radiate from an entrance wound travel faster than bullet (Dixon) Can result in an atypical exit wound Example—a semicircular exit rather than a complete circle; fracture traveled faster; absorbed energy;result;semi-circular exit wound Another type of bullet entrance wound, a tangential or glancing, or angled, bullet entry position, skips across skull Fan shaped defect called a keyhole lesion In such a case, projectile not only bevels bone inward but also chips it to product an outward bevel What about post cranial projectile wounds? Can they be distinguished from blunt force? in some cases yes Example Entry wound Extrinsic ForcesTraumaShape, weight, material of striking object Rates and duration of loading at impact site Relative force of blow As noted earlier, initial force bends bone Bone resists due to its structure—if force is low rate and compressive and tensile strength are able to resis In this “elastic” stage, bone can return to normal shape when pressure is removed If pressure increases, bone enters plastic deformation and can no longer regain its original shape—it is at a unique yield point Once extrinsic factors exceed the resisting strength, bone fails; fracture occurs Butterfly fractures Types of fractures Linear Line Single fracture Stellate Star Multiple fractures coming out from point of injury Compression Compressing the bone Fibula and tibia example Oblique At an angle Common in long bones Compound Breaking the bone in half Pond Radiating circles on fracture Police flashlight Ripples in pond Hinge One side broken away, similar to greenstick fracture Comminuted Multiple bones and breaks in same bone Greekstick One side broken, one just bent Ribs Sharp Force Trauma Blunt force blow delivered by sharp object Easier to determine angle in clothing and soft tissue Much more challenging in bone Injury may never contact bone Blunt trauma to rib may represent force used to stab person without actually incising bone Elastic skin and organs must be considered when trying to assess direction of sharp trauma Maybe be able to suggest single edged blade, double edged blade, width, thickness, serrated, straight, spine features, hilt shape Easier to look at the knife and predict the wound it will make than to look at a wound and suggest the type of instrument that made itTraumaExamples Ante mortem trauma can help ID Button osteoma Benign bony


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LSU SOCL 2001 - Trauma

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