Chapter 7 Physical Trauma

 For each type of injury listed, propose the type of weapon/instrument that might cause that type of injury.  Abrasion  Chop wound  Contusion  Hesitation marks  Laceration  Therapeutic wound Vocabulary

 Work with the person sitting next to you to come up with a definition of physical trauma  Provide 5 examples of physical trauma  Which of your examples are life threatening? Physical Trauma

 Choose a partner and stand 3 feet apart and face each other  Pretend to hold a knife in your left hand and model a stabbing motion  Observe the angle at which the knife hits the victim  Repeat the procedure with your right hand then switch roles with your partner How can you tell if the agressor is right-handed or left-handed?

 2008 – 11 million crimes of which 1.3 million were violent  Of the 1.3 million violent crimes 16,000 resulted in death and the remainder suffered from physical trauma  Physical trauma – any serious or life-threatening physical injury, wound, or shock Introduction

 1. blunt-force – victim hits or is hit by a hard object  2. sharp-force – victim is poked, cut, or stabbed by something sharp Types of physical trauma

 Evaluates the physical trauma and interprets the injuries  Can provide a profile of the suspect  For example: What will the angle of the impact tell you about the suspect?  What about the location of the trauma? Forensic Nurse

 Appearance and extent of injuries depend on the following:  A) amount of force applied to body  B) mass and surface area of weapon  C) part of the body affected Evidence of Physical Trauma

 A push or a pull applied to an object  Calculation  Force = mass x acceleration(F=ma)  Acceleration is the change in velocity over a period of time  Ex) a car traveling at 45 mph – it’s velocity = 45 mph or 2o meters per second  If the car suddenly stops then the change in velocity = 20 meters per second  If it takes 2 seconds to stop then the acceleration is 10 meters/s/s or 10 m/s 2 (this is negative acceleration) Force

 1. How would the force change if the vehicle in the previous problem had a greater mass? Substitute the mass with a different number to support your answer.  An attacker swings a board with a mass of 2 kg toward a victim. The acceleration is 10m/s2 when the board hits the victim. How much force did the board exert on the victim? Practice problems

 If the same amount of force is exerted over a larger surface area, the injury will be less severe because pressure = amount of force per unit area or P = F/A  Ex) if you push against a wall with your palm that has a surface area of 129 cm2 using 44.5 N of force, what is the pressure?  Ex) now use the same force but with a closed fist that has a surface area of 38.7 cm2  How does the pressure change?  Why do women wearing high-heeled shoes walk on the tips of their toes when walking on soft surfaces such as a muddy lawn?  T or F A weapon with a larger surface area will inflict a less severe injury if force is kept constant. Surface Area and Pressure

 Develop 3 force word problems  1 should have you solving for force  1 should have you solving for mass  1 should have you solving for acceleration  Problem should be centered on a victim who suffered from a specific kind of trauma Creating your own word problems

 1. Blunt force trauma – hit by something hard, falls or is pushed into a hard object  2. Sharp force trauma – injury caused by sharp or pointed weapon Types of Trauma

 1. Abrasions – if part of the body rubs against a rough surface -  portion of the epidermis may be removed Blunt force trauma

 1. receptors to detect pain, touch, pressure, and heat  2. temperature regulation  3. excretion  4. prevent water loss  5. protect body against pathogens Function of skin

 When force is applied parallel to the skin – ex) if victim is dragged along a rough surface  Skin is damaged in the direction of the force  Wound may contain debris, gravel, or glass  May also be produced by a noose or tie that would leave fibers A. Brush Abrasions

 When force is applied perpendicular to the skin/skin may be crushed B. Impact abrasions

 If the object leaves a pattern on the skin C. Patterned abrasion

 Aka – bruise – broken blood vessels below the surface of the skin or involving internal organs  Contusion vs livor mortis – how to tell the difference  Called a hematoma if blood causes swelling – ex) subdural hematoma  Severity determined by force and type of tissue  Patterned contusion  Use CT scan to visualize contusions to internal organs  Children and elderly most vulnerable to bruising  Bleeding disorders also increase the likelihood of bruising  Shock – extensive blood loss Blunt Force Trauma - Contusions

 Laceration – a tear in the tissue caused by sliding or crushing force  - caused by extreme force from a blunt object  - irregular edges, may have pattern  - may occur internally or externally  Defensive Wounds – abrasions and contusions on hands, wrists, or arms  - may hold trace evidence from weapon  - called offensive wounds if perpetrator is injured Blunt Force Trauma – Lacerations and Defensive Wounds

 Sharp weapons such as knives  4 categories – stab, incised, chop, or therapeutic Sharp Force Trauma

 Most are caused by single-edged kitchen, pocket, or folding knives/4-5 inch blade  Hesitation marks  Perforating vs penetrating wound  Hilt – may leave patterned abrasion Stab Wounds

 Wound is longer than it is deep because force is applied parallel to the skin  Do not offer clues about the weapon  Generally not fatal  Can be defensive wounds Incised Wound

 Tools such as axes, machetes, and meat cleavers  Surface and internal injuries that sometimes include bone fractures  Examination of bone markings can differentiate a cleaver from a machete  Therapeutic wound – produced as a result of surgery Chop wound and therapeutic wounds

 For each of the types of blunt force and sharp force trauma described in your textbook, create a table that includes the following information:  Name of injury  Possible weapon  Description of injury  Due before you leave today and may be used on test tomorrow. Assignment