Forensic Anthropology Lecture Notes. Week 3: Crime Scene Analysis, Trauma and Taphonomy

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Lionel Hampton
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1 Frensic Anthrplgy Lecture Ntes Week 3: Crime Scene Analysis, Trauma and Taphnmy Mdule 16: Blunt Frce Trauma What is Blunt Frce Trauma? Blunt frce trauma ccurs any time a frce impacts tissue ver a relatively wide area. This includes sme basic types f injury: Blunt instruments (crwbars, baseball bats) Car/train/airplane crashes Abrasins f all kinds (incl. rad rash ) Bites Falls Basic Blunt Frce Terminlgy A LACERATION is a tear in the skin caused by a blunt instrument. This is nt the same thing as a cut! A CONTUSION is a bruise An ABRASION means a superficial scraping and/r stretching Laceratins A laceratin (rip r tear) can be distinguished frm a sharp-frce injury with sme ease, althugh n grss examinatin they will appear similar Laceratins ften have cntusins, strings f flesh Cntusins Cntusins r bruises are almst always blunt frce A bruise changes in clr frm light bluish red t dark purple, then t green, then t yellw, then t brwn. This can help yu t tell the difference between anteand Perimrtem trauma Als, a bruise may nt be immediately apparent n initial examinatin, but may becme readily bservable sme hurs r days later.

2 Abrasins An abrasin is the scraping and remval f superficial layers f skin Rad rash bdy dragged alng paved area Stretching abrasin caused by stretching f skin beynd its elastic tlerance, as is als ften seen in rad accidents. Characteristics r Instruments The size f the weapn Width f the area between the cntusins generally crrespnds with the width f weapn Lng Axis (length): can smetimes be estimated frm dimensins f injury Shrt Axis (width): an bject with a small width needs less frce t cause injury than ne that is brader The shape f the weapn We want t assess the crss sectinal and lngitudinal dimensins f the weapn Rund: clubs, baseball bats, glass bttles Angular: sme crwbars, lumbar, etc. Mre likely t leave distinct marks Distinct edges Fewer fracture lines Mst likely t leave imprint f shape n bne The weight f the weapn Obviusly, a 12z can f sup will cause less damage than a 4 lb. baseball bat Heavy instruments can cause catastrphic fractures resulting in large wunds with extensive crushing and fragmentatin Hwever, a 12z can f sup can cause an injury just as fatal if hurled with sufficient frce

3 Frce f impact is mre imprtant than the weight f the bject used Effects n Bne are minimally Diagnstic Length is almst impssible t ID in a skeletnized individual Width perhaps but als unlikely Mre likely t state whether frce was fcused r diffused Small width less frce t cause serius damage, therefre sme estimate f size is necessary Effects f Blunt Instruments The Skull Yuthful, elastic bne defrms inwardly at the pint f impact. This means the uter table is under cmpressin while the inner table is under tensin Bne is mre susceptible t tensin Therefre the bne breaks frm the inner surface ut Buttressing and Frce Fur main buttresses f the cranial vault Mid-ccipital Psterir tempral Anterir tempral Midfrntal Frce frm a blw t the vault will cause fractures between these buttresses Blunt Trauma t the Face The bnes f the face actually have regins f buttressing that guide the dissipatin f frce The bne areas surrunding these buttresses are weaker and thus mre prne t fracture Face breaks ften cnfrm t well-knwn patterns called LeFrt Fractures. There are three classic varieties LeFrt Fractures

4 LEFORT I The paired maxilla shatters straight acrss This separates the upper teeth and alvelar bne frm the rest f the skull This is caused by a blw t the lwer face LEFORT II The midface separates frm the rest f the cranium This is caused by an anterir blw t the midface LEFORT III This separates the face frm the cranial vault It is caused by a centrally fcused blw t the upper face Ring Fracture t Cranial Base Results frm either tensin r cmpressin at the cranium-vertebra interface Can ID tensin r cmpressin by the beveling f the fracture line Mre French Names: Cup-Cntrecup Cup-cntrecup injuries result frm the same blw, but cause tw different wunds ppsite ne anther This is because the frce f impact has a cunterfrce In the case f smene hitting their head in a fall, ne injury is frm the impact and the ther is frm the crrespnding negative pressure exerted ppsite t that pint. Wund Analysis Descriptin f the wunds as t number, lcatin, etc. Estimatin f size nly in rare cases Estimatin f shape nly in rare cases, extremely fcused trauma r with angled bject Directin f the blw fairly straightfrward

5 Estimatin f energy very tugh, speed and weight determine energy, size, f bject crucial Estimatin f number f blw easy if distinct areas affected, flaking f fracture edges indicates repeated blws t same area Estimatin f sequence tracing fracture lines

Chapter 13 Forensic Anthropology: What We Learn from Bones By the end of this chapter you will be able to:

Chapter 13 Forensic Anthropology: What We Learn from Bones By the end of this chapter you will be able to: Chapter 13 Frensic Anthrplgy: What We Learn frm Bnes By the end f this chapter yu will be able t: Describe hw bne is frmed Distinguish between male and female skeletal remains Explain hw bnes cntain a