Chapter 7 Physical Trauma © 2012 Cengage Learning. All Rights Reserved

Introduction—Objectives 1. Discuss how investigators study injuries to determine the extent, or degree, of injury. 2. Differentiate between the three types of blunt-force trauma. 3. Discuss the four types of sharp-force trauma. Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 2

3 Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 3 The Siren and the Slugger Rihanna and Chris Brown A verbal argument erupted into a physical confrontation Brown caused contusions to form on Rihanna’s forehead, left hand, left triceps He bit two of her fingers Brown turned himself in, pled guilty to felony assault

Introduction Physical trauma—any serious or life- threatening physical injury, wound, or shock Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 4

Evidence of Physical Trauma (Obj 7.1) The extent of the physical trauma depends on – the amount of force applied to the body, – the part of the body affected, – how much of the body’s surface was affected, and – the type of weapon used Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 5

Force is equal to mass times acceleration. The more massive the weapon, the greater the force exerted on the body. The more the weapon is accelerating upon impact, the greater the force exerted on the body. Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 6

Force Force = mass x acceleration Force is a push or pull applied to an object Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 7

Surface Area and Pressure Pressure = force / surface area Pressure is the amount of force per unit area A weapon with a larger surface area will inflict a less severe injury – High-heeled shoe – Ping Pong paddle Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 8

Types of Trauma Injuries to the body are usually classified as either blunt-force or sharp-force trauma. This classification is based on the type of wound produced and the weapon used. Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 9

Blunt-Force Trauma (Obj 7.2) Caused when a victim: hits or is hit by a hard object falls or is pushed into a hard Types of Blunt force traumas Abrasions Contusions Lacerations Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 10

Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 11 Massive abdominal blunt force injury often leads to liver injury, since it is the largest internal organ. Note the multiple lacerations over the capsule. Damage to abdominal organs with lacerations, crush injuries, and rupture can lead to bleeding into the peritoneal cavity known as hemoperitoneum. A peritoneal lavage can detect such bleeding.

abrasion - an injury in which the superficial, or top, layer of skin has been removed due to motion against a rough surface Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 12

Blunt-Force Trauma—Abrasions Skin has three layers – Epidermis – Dermis – Hypodermis Abrasion affects the epidermis, or outer layer Shallow wounds that heal quickly Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 13

Blunt-Force Trauma—Abrasions Brush Abrasions – When force is applied parallel to the skin – Example: dragging the body Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 14

Blunt-Force Trauma—Abrasions Impact Abrasions – When force is applied perpendicular to the skin – Crushes the skin – Common over bony parts of the body Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 15

Patterned Abrasions – When the impact of an object leaves an imprint on the skin – Patterns can be used to identify the weapon Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 16

Blunt-Force Trauma—Contusions Also known as a bruise A trauma caused by broken blood vessels below the skin’s surface Hematoma—when contusions swell Subdural hematoma— swelling below the brain’s outer membrane Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 17

Blunt-Force Trauma—Contusions Patterned contusions- when the bruise looks similar to the object that produced it. The pattern can give information as to the object used to commit the crime. Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 18

Subdural Hematoma Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 19

Blunt-Force Trauma—Contusions Contusions on internal organs are not visible externally CT Scan-use x-rays to check for contusions in deep tissues and organs Factors that make internal contusions difficult to detect are: Skin pigmentation makes detection more difficult Obese vs. athletic bodies Children and seniors Alcoholics Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 20

Blunt-Force Trauma—Lacerations A tear in the tissue caused by an extreme sliding or crushing force – Blunt objects – A fall – Vehicle impacts Lacerations may be internal or external Irregular edges Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 21

Blunt-Force Trauma— Defensive & Offensive Wounds Defensive wounds—usually occur on the hands, wrists, and arms Offensive wounds—injuries to the perpetrator These wounds help substantiate claims by the victim and perpetrator Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 22

Sharp-Force Trauma (Obj 7.3) Sharp-force trauma—when the victim is poked, cut, or stabbed by something sharp Stab Wounds Incised Wounds Chop Wounds Therapeutic Wounds Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 23

Stab Wounds Most are caused by single-edged kitchen, pocket, or folding knives Blade is usually 4-5 inches long A sharp knife requires very little force Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 24

Stab Wound: Single Edge Blade Sharp edge of blade

Stab Wounds hesitation marks - jagged and rough superficial wounds caused by someone attempting to take their own life, caused as the person responds to the pain Hesitation marks—by suicide victims Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 26

Stab Wounds Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 27

hilt - protective piece where the blade meets the handle of a knife Penetrating wound—puncturing the organ Perforating wound—passes all the way through the organ Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 28

Incised Wounds incised wounds - cuts along the surface of the body. Produced by sharp-edged objects such as knife, glass, metal, or paper Longer than deep Force usually applied parallel to the skin Do not provide clues to the type of weapon Clean edges Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 29

Chop Wounds chop wound - wounds that result in cuts (incised wounds) on the surface and deep internal injuries and/or fractures to bones Heavy tools—axes, machete, meat cleavers Incised wounds on the surface Deep internal injuries Bone fractures Characteristics of the wound help narrow down the possible type of weapon used Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 30

Chop Wounds WeaponCharacteristics AxeOften crushes the bone and tissue MacheteProduce more obvious lines that are coarse and less distinct Meat CleaverClean thin wound; unlikely to break bone; thin, sharp lines on the bone 31 Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved

Therapeutic Wounds Caused by surgery or other medical procedures Avoid confusion between therapeutic and inflicted wounds Inflicted wounds are criminal wounds like stab wounds Forensic Science II: Physical Trauma, Chapter 7 © 2012 Cengage Learning. All Rights Reserved 32