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Forensics

Types of injuries

Blunt force and sharp force injuries


Author: Lindsey Harle, M.D. (see Reviewers page)
Revised: 26 March 2012, last major update March 2012
Copyright: (c) 2012, PathologyOutlines.com, Inc.

Blunt force injuries
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● Injury causes by a blunt object striking the body or the body impacting a blunt surface

Abrasion: injury to superficial skin epithelium due to sliding force, compression or pressure; i.e. scrape
Patterned abrasion: injury in which a pattern is transferred from the impacting object or intermediary material (i.e. clothing); can be used to identify weapon
● Road rash is an abrasion caused by the road surface; commonly seen in pedestrian-motor vehicle accidents (MVA) or bicycle accidents
● Antemortem abrasions are usually red-brown; postmortem abrasions are yellow or transparent (due to absence of blood flow)

Contusion: bleeding into skin or soft tissue due to ruptured blood vessels; i.e. bruise
● Can occur on skin, subcutaneous tissue or internal organs
● As with abrasions, can be patterned
● May not correspond to sight of impact; i.e., contrecoup contusions in the brain occur opposite to site of impact
● Senile ecchymoses in elderly should not be mistaken for significant blunt force injury; these occur with relatively minor trauma
● Color change over time: not necessarily reliable to indicate age of injury, but generally red/purple initially, then green/yellow over time

Laceration: tear in tissue due to blunt force injury
● Commonly occurs over boney prominences; can occur in internal organs
● Differentiated from sharp force injury (i.e. incision) by the presence of tissue bridging across the depths of the wound

Sharp force injuries
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● Injury caused by sharp or pointed weapons
● Differentiated from lacerations by the absence of tissue bridging within the wound

Stab wound: injury from sharp weapon that is deeper than it is wide
● Common weapons include knife, ice pick, scissors, fork
● Stab wound on the skin should be examined to determine if it has sharp or blunt margins; this can be used to determine if the weapon had a single edged or double-edged blade
● Weapons such as a screwdriver, fork or serrated knife can leave distinctive skin patterns that can be matched to the weapon
● Depth of penetration of the wound does not directly correlate with the length of the weapon, as it can be longer, shorter, or equal to the weapon length depending upon the amount of force applied and the location on the body
● Likewise, the length of the wound on the skin may be longer, shorter or equal to the weapon's for the same reasons
● The guard of the knife may produce a patterned abrasion if it is stabbed with significant force into the skin; this can aid in identifying the weapon
● If the weapon comes into contact with bone, the tip may break off and remain in the body; this can be used to identify the weapon
● Suicidal stab wounds may show hesitation marks; i.e. multiple superficial stab wounds surrounding the final, fatal wound
● Defense stab wounds can be found on the hands and extensor surfaces of the arms in homicidal stabbings

Incised wound: sharp force injury that is longer (as measured on the skin) than it is deep
● Usually not fatal, except when they occur over major arteries (i.e. on the neck/arms)
● As with stab wounds, suicidal incised wounds may be associated with hesitation marks; these marks do not rule out homicide
● Defensive incised wounds occur on the hands and extensor surfaces of the arms in homicides

Chop wound: due to a heavy weapon that has a sharp edge, i.e. machete, axe, boat propeller
● Commonly produces an incised wound associated with a cut into the underlying bone
● Dull chop weapons, such as a shovel, produces more crush injury than sharp force injury

End of Forensics > Types of injuries > Blunt force and sharp force injuries


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