Penetrating TraumaSections Introduction to Penetrating TraumaPhysics of Penetrating TraumaSpecific Tissue/Organ InjuriesSpecial Concerns with Penetrating Trauma38,000 Deaths in US annually due to shootings.Mechanisms of penetrating traumaKnives, Arrows, Nails, etcUnderstanding principles of energy exchange increase the Index of Suspicion associated with the MOIIntroduction to Penetrating TraumaRecall Kinetic Energy EquationGreater the mass the greater the energyDouble mass = double KEGreater the speed the greater the energyDouble speed = 4x increase KEPhysics of Penetrating Trauma(continued)Physics of Penetrating TraumaSmall & Fast bullet can cause greater damage than large and slow.Different bullets of different weights traveling at different speeds causeLow Energy/Low VelocityKnives and arrowsMedium Energy/Medium Velocity WeaponsHandguns, shotguns, low-powered rifles250-400 mpsHigh Energy/High VelocityAssault Rifles600-1,000 mps(continued)Physics of Penetrating TraumaBullet spins as it travels down barrelRifling in barrelAllows bullet to travel straight with slight yawBullet departs barrel, spinning with a slight wobble or yawWeapon forced backward and absorbs energyRecoil(continued)Physics of Penetrating TraumaRemainder of energy propels bullet forward at a high rate of speed.Trajectory is curved due to gravityAs bullet strikes object, it slows and energy is transferred to object.Law of Conservation of EnergyBallisticsStudy of the characteristics of projectiles in motion and effects upon objects impactedFactors affecting energy exchange between a projectile and body tissueVelocityProfileStabilityExpansion & FragmentationSecondary ImpactsShapeEnergy DissipationDrag: wind resistanceCavitation: formation of a partial vacuum and cavity within a semi-fluid mediumProfile: Size and shape of a projectile as it contacts a targetLarger the profile=greater energy exchangeExpansion and fragmentation results in damageStabilityAllows for straighter trajectoryDecreases after striking object results in tumblingAspects of BallisticsVelocityCauses TrajectoryFaster = straighter trajectorySlower = more curved due to gravityAspects of BallisticsProfilePortion of bullet you see as it travels towards youLarger profile = greater energy exchangeCaliberDiameter of a bullet (ID of gun)0.22 caliber = 0.22 inchesBullets become unstable as they pass from one medium to another.Aspects of BallisticsStabilityBullet length increases bullet tumblingCan reduce the accuracy of the shotReduced by Rifling in barrel (spinning)YawGyroscopic effect on the center axis of the bullet that reduces tumblingTumbling of bullet once it strikes objectReduces kinetic energyGreater tissue damageBullet Gyroscopic EffectAspects of BallisticsExpansion & FragmentationResults in increased profileMushroomingInitial impact forces may result in fragmentingGreater tissue damageAspects of BallisticsSecondary ImpactsBullet striking other objects can cause yaw and tumbleBody Armor (Kevlar)Transmits energy throughout entire vest resulting in blunt traumaMyocardial ContusionPulmonary ContusionRib FracturesShapeHandgun Ammunition = Blunt = TumbleRifle Ammunition = Pointed = PiercingHandgunsSmall caliber, short barrel, medium-velocityEffective at close rangeSeverity of injury based upon organs damagedRifleHigh-velocity, longer barrel, large caliberIncreased accuracy at far distancesAssault RiflesLarge magazine, semi- or full-automaticSimilar injury to hunting riflesMultiple woundsSpecific Weapon CharacteristicsShotgunSlug or pellets at medium velocity00 (1/3”) to #9 (pin head sized)Larger the load, the smaller the number of projectilesDeadly at close rangeKnives & ArrowsLow-energy & low-velocityDamage related to depth and angle of attackMovement of the victim can increase damageSpecific Weapon CharacteristicsDamage PathwayProjectile Injury ProcessTip impacts tissueTissue pushed forward and to the sideTissue collides with adjacent tissueShock wave of pressure forward and lateralMoves perpendicular to bullet pathRapid compression, crushes and tears tissueCavity forms behind bullet pulling in debris with suction.Damage PathwayDirect InjuryDamage done as the projectile strikes tissuePressure Shock WaveHuman tissue is semi-fluidSolid and dense organs are damaged greatlyTemporary CavityDue to cavitationPermanent CavityDue to seriously damaged tissueZone of InjuryArea that extends beyond the area of permanent injuryBallistics CavitationLow-Velocity WoundsObjectsKnives, Ice-picks, ArrowsFlying objects or debrisInjury limited to tissue impactedObject pathwayObject twisting or movedOblique angleAttacker CharacteristicsMales: outward and crosswiseFemales: overhand and downwardDensity of tissue affects the efficiency of energy transmissionResiliencyStrength and elasticity of an objectConnective TissueAbsorbs energy and limits tissue damageOrgansSolid OrgansDense and low resilienceHollow OrgansFluid filled: transmit energy = increased damageAir filled: absorbs energy = less damageSpec。