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Blunt Force Trauma Slide 2 DEFINITION OF WOUNDS Medical definition: Disruption of the continuity of the tissues produced by external mechanical force. Legal definition: Breach of the full thickness of the skin Slide 3 Wounds Medico legal divisions of wounds 1- accidental 2- sucidal 3- homicidal 4- self inflecting Slide 4 Slide 5 Blunt Force Trauma There are Four Main Divisions of Blunt Force Type Injuries. They are: Abrasions or scrapes: scratches and grazes Contusions or Bruises (leakage of blood from vessels = extravation) Extra = outside; vasa = vessel Lacerations or Tears Fractures of Bone(s) Slide 6 Types of wounds Abrasions Bruises Lacerations Incised Wounds Slide 7 Types of wounds Slide 8 Blunt Trauma The severity of blunt trauma depends on: Amount of force delivered Time over which the force is delivered Region struck Extent of body surface struck Nature of the Weapon Slide 9 Blunt Trauma Wounds If a weapon breaks on impact less energy is delivered to the body If the body moves with the blow less energy is delivered to the body Slide 10 Blunt Trauma Wounds The larger the area over which the blow is delivered the less severe the injury An object that projects from the weapon will deliver all of the force Rounded portions of the body can sustain greater injuries Slide 11 ABRASIONS There are three types of Abrasions - Impact - Patterned - Scrapes Slide 12 Abrasions It is the most superficial type of injuries that does not penetrate the full thickness of the skin (usually confined to the epidermis).It is the most superficial type of injuries that does not penetrate the full thickness of the skin (usually confined to the epidermis). Usually caused by blunt force trauma.Usually caused by blunt force trauma. Slide 13 Characteristics of Abrasions They are usually not life threatening although they are painful.They are usually not life threatening although they are painful. They heel without scarring.They heel without scarring. Bleeding/Exudation is slight and leads to crust/scab formation.Bleeding/Exudation is slight and leads to crust/scab formation. Might be associated with bruising and lacerationMight be associated with bruising and laceration Slide 14 Blunt Trauma Wounds Abrasions: An injury in which there is removal of outer layers of tissue by compression or a sliding force Indicates EXACT site of contact or impact In living persons the wound will scab over and become dry and darken Postmortem the wound is yellow with a parchment-like appearance Slide 15 Slide 16 What is the Forensic Significance of Abrasions? Indicates violence Its shape gives an idea about the causal instrument Bite abrasions take the pattern of the teeth Site of abrasion denotes the type of crime Age of abrasion can be estimated so the time of the incident is known Helps in identification of the assailant as in bite abrasion Slide 17 Slide 18 Types of abrasions Direct vertical impact: 1)The force is usually applied vertically onto the skin and causes crushing of the epidermis. 2)The causative object may stamp its shape on the skin. Examples: Fingernail impression and bite mark, and marks of a vehicle radiator on a pedestrian victim or the pattern of a floor grid on to which a person has fallen. Fingernail impression and bite mark, and marks of a vehicle radiator on a pedestrian victim or the pattern of a floor grid on to which a person has fallen. Slide 19 Slide 20 Types of abrasions Tangential impact( brush abrasions) : Loss or scraping of the epidermis due to friction against a rough surface (graze) or a sharp surface (scratch) Loss or scraping of the epidermis due to friction against a rough surface (graze) or a sharp surface (scratch) Broader surfaceBroader surface Slide 21 This example of brush abrasions. It illustrates a motorcycle fatality, where the victim has come in contact with the road surface. Example of a brush abrasion of the abdomen by scraping along a rough sooted and rusty surface of a metal tank during a fall. Slide 22 Slide 23 Types of Abrasions Impact Abrasions The blunt force is perpendicular to the surface of the body Mostly seen over bony process Eyebrows Cheekbone Nose Slide 24 Types of Abrasions Slide 25 Blunt Trauma Wound Patterned Abrasions This occurs when the object which impacts the body leaves an imprint or stamp on the skin Be aware postmortem insect bites may resemble patterned abrasions Slide 26 Patterned Abrasion Slide 27 Types of abrasions Fingernail abrasions Fingernail abrasions These are important because of their frequency in assaults especially child abuse, sexual attacks and strangulationsThese are important because of their frequency in assaults especially child abuse, sexual attacks and strangulations Often associated with focal bruises.Often associated with focal bruises. Fingernails abrasions are most often seen on the neck, face, and the upper arms and the forearm Slide 28 Fingernail Abrasions Slide 29 Slide 30 Slide 31 Blunt Trauma Wounds Scrapes A blunt objects takes off the top layers of skin May go as deep as the dermis Leakage of fluids (serosanguineous fluid) The area is reddish brown and forms a scab Slide 32 Bruising and abrasions along the right side and on the abdomen could have come from a number of causes, including being dragged & pushed down to the ground. Slide 33 Types of abrasions Post mortem abrasions: Unlike post mortem bruises, artifactual abrasions are common.Unlike post mortem bruises, artifactual abrasions are common. They may have been inflicted after death from a variety of causes, including dragging a corpse or buffering in moving water. Some post mortem animal injuries resemble abrasions such as insect bites.They may have been inflicted after death from a variety of causes, including dragging a corpse or buffering in moving water. Some post mortem animal injuries resemble abrasions such as insect bites. Slide 34 Slide 35 Slide 36 Blunt Trauma Wound Dating Abrasions is a complicated process Scab formation begins in 4-6 hrs and is usually complete in 18 hrs The skin underneath the scab begins to regenerate within 72 hrs Once the scab falls off the skin will remodel and become thinner after about 12 days Slide 37 Importance of abrasions in forensics Always reflects the site of impact.Always reflects the site of impact. Often indicates the causative agent.Often indicates the causative agent. Often indicates the direction of impact.Often indicates the direction of impact. Helps in determining the time of injuryHelps in determining the time of injury. Slide 38 Slide 39 Importance of abrasions in forensics Helps in determining the time of injury: Helps in determining the time of injury: Fresh: hyperemia, oozing serum and usually without bleeding. Up to 36 hours: hyperemia and soft yellow crust of dried serum. 2-3 days: dry brown scab. 6-7 days: falling of scab leaving a red surface which disappears without leaving a scar within 2-3 weeks. Slide 40