Forensic Anthropology Beginning of Week 4/18/16
Forensic Anthropology Beginning of Week 4/18/16 Anth 310
Edinboro University of Pennsylvania
Popular in Intro to Forensic Anthropology
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This 6 page Class Notes was uploaded by Danielle Johnson on Sunday April 24, 2016. The Class Notes belongs to Anth 310 at Edinboro University of Pennsylvania taught by Dr. Barbian in Winter 2016. Since its upload, it has received 15 views. For similar materials see Intro to Forensic Anthropology in anthropology, evolution, sphr at Edinboro University of Pennsylvania.
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Date Created: 04/24/16
Forensic Anthropology Beginning of Week 4/18/16 Force continued Speed of Force ● Dynamic Force ○ Force delivered powerfully and at high speed ○ Most common force ○ Bludgeon, knife, projectile ● Static Force ○ Force delivered slowly ○ Starts low and builds to point where bone breaks ○ Strangulation Focus of the Force ● Narrow Focus: force applied to single point or thins line ○ Delivered by pointed or sharpedged instrument ● Wide Focus: force delivered to large are of bone ○ Ranges 16’ ○ Delivered by an mechanism other than cutting or chopping instrument Five Types of Trauma ● Blunt→ slow trauma ● Sharp→ slow trauma ● Projectile trauma → Rapid trauma ● Burn Trauma ● Miscellaneus Slow vs. Rapid Trauma ● Slow trauma ○ Plastic deformation: site of impact is forced inward ○ Fragments are difficult to match up ● Fast trauma ○ Elastic deformation: site of impact is forced outward ○ Fragments are easily matched Blunt Force Trauma ● Injury caused by wide focus of impact ● Result of compression, bending, or shearing forces ○ Low load: lowforce injury from an object hitting a person ○ High load: highforce injury from an object hitting a person or a person hitting a stationary object ● Bone is stronger in compression than tension ○ failure(break) occurs first in tension, on the opposite side of impact ● Stages of bone reaction ○ Stress: force applied with bending or distortion Forensic Anthropology Beginning of Week 4/18/16 ○ Strain: resilient bending under load ○ Plastic deformation: bending with permanent deformation ○ Fracture: failure ● Rules to remember: ○ Don’t let the shape of the wound influence you ○ Skin is often better than bone in determining blunt trauma ○ The skin is not a baloon → impact on one side does not cause action on the other Blunt Force to the Skull ● Four phases ○ In Bending at impact site, without bending surrounding the impact site ○ Fracture lines begin on out bent surface and progress both inward and outward→ radiation features ○ Wedge shape pieces of bones ○ Concentric fractures Sharp Force Trauma ● Injury caused by narrow focus of impact ● Result of compression or shearing forces ● Wounds appear in different forms depending on direction,focus and energy of the force ○ Puncture ■ Vertical force with coneshaped focus ○ Incision ■ Defects longer than they are wide ○ Cleft or notch ■ Vertical force by an instrument with long, sharp edge Projectile Trauma ● Injury caused initially by narrow focus, becoming wider as projectile passes through the bone ● Results of compression or bending forces Effects of Bullets on Bone ● Wound beveling ○ Entrance wound vs. exit wound ■ As a bullet enters bone, it becomes deformed, causing a large exit wound ■ Creates a funnel shape ○ Three types ■ Inward beveling ● Site of bullet entry ● Hole on outer surface is smaller than hole on inner surface ■ Outward beveling Forensic Anthropology Beginning of Week 4/18/16 ● Site of bullet exit ● Hole on inner surface is smaller than hole on outer surface ■ Reverse beveling ● Wound Shape ○ Four factors affecting shape: ■ Bullet construction ■ Angle of trajectory ■ Angle of axis ■ Type of wound (entry or exit) ○ Four shapes ■ Round ● Circular in outline ● Both angle of trajectory and angle of bullet axis are perpendicular to bone surface ● Most common in: ○ Entry wounds ○ Smaller opening of the bevel ● Round exit would often cause by jacketed projectile ■ Oval ● Elliptical in outline ● Angle between bullet axis and bone surface is <90degrees ○ Occurs when: ■ Angle of trajectory is not perpendicular to bone surface ■ Bullet is tumbling when it strikes ● Most common: ○ Entry wounds ○ Smaller opening of the bevel ■ Keyhole ● Outline is circular on one end and triangular on other ● Bullet grazes bone surface ● Constitute both entry and exit wound ○ Entry=round with inward beveling ○ Exit=triangular with outward beveling ● Seen most often in the skull ■ Irregular ● Outline lacks uniformity and general pattern ● Examples ○ Jagged circular ○ Asymmetric stellar ○ Irregular rectangular ● Result of bone shattering ● Most common in exit wounds Forensic Anthropology Beginning of Week 4/18/16 ● Caused by blunt and hollowpoint bullets ● Wound size ○ Biggest Factors ■ Wound type ● Exit wound are generally larger than entrance wounds ■ Bullet characteristics ● Larger caliber ammo= larger wound ○ Additional factors ■ Thickness of bone ● Thicker bone causes more deformation of bullet= larger entrance wound ■ Age of the individual ● Younger individuals have more elastic to their bones, so they ahve a smaller entrance wound ● Fracture lines ○ More powerful weapons cause more extensive fracturing ○ Two type of cranial fracture lines ■ Radiating ● Lines moving outward in any direction from the point of impact ● Often seen in entrance wounds ● Follow ares of the vault that are weakest ■ Concentric ● Lines appearing as part of all of a circle whose center is the point of impact ● Caused by intracranial pressure created by the bullet ● Miscellaneous Trauma ○ Strangulation ■ Caused by static pressure ■ May be seen in hyoid fractures, but prevalence is low ○ Chemical trauma ■ Slow poisoning can be detected by abnormal presence of toxic heavy metals in bone tissues Fire Modification of Bone ● How does Fire affect Forensic Anthro? ○ Hinder personal id ○ Make biological profile assessments difficult ○ Conceal evidence of crime ● General Rule ○ Bodies are not easily obliterated by fire Forensic Anthropology Beginning of Week 4/18/16 ■ Identifiable material should remain even after prolonged exposure to very high temps ● Degrees of Fire modification ○ Degree of thermal alteration is based on amount of surviving tissue ■ Charring: internal organs remain ■ Partial cremation: soft tissues remain ■ INcomplete cremated bone fragments remain ■ Complete cremation: only ash remains ○ Single element may exhibit instances of each classification→ exposure variability ● Fire Process signatures ○ Bodies burn in a uniform, recognizable pattern if all external variables are similar ○ Important to remember that bones burn as part of a fleshed body, not dissociated skeletal elements ○ Three signatures: ■ Body position and tissue shielding of bone ● Pugilistic pose ○ Posture induced by fire and heat ○ Heat promotes muscle contraction and shrinkage ○ Most powerful muscles (flexors) and ligaments overpower ● Pugilistic pose reults in increased exposer of specific areas and shielding of others ● Degree of modification is predictable across body ○ First to burn ■ Wrist and back of hands ■ Posterior elbow ■ Knee ○ Last to burn ■ Palms ■ Pelvis ■ midthigh ■ Color change in bone ● Heat produces a gradient of colors as bone dehydrates and becomes exposed ● Generally, bones burn from the outside to the inside ● 5 recognizable color pants ○ Heat Line ■ Area of initial transition from unaltered to heataltered bone ■ Appears occasionally ● Border ○ Offwhite are protected from contact with smoke and flames by receding soft tissue Forensic Anthropology Beginning of Week 4/18/16 ○ Varies in width ○ Flaking often seen in outer cortical ○ ■ Burned bone fracture biomechanics
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