Chop-injury circumstances and stab-wound characteristics
THE CONTEXT
The passage completes the discussion of chop injuries and introduces the mechanism, types and margins of stab wounds.
Chop injuries
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A tangential chopping blow may remove a disk-shaped portion of bone, skin or soft tissue. The neck may be almost completely separated.
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Most chop injuries are homicidal and involve exposed sites such as the head, face, neck, shoulders and extremities. Suicidal chop injuries are very rare.
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Accidental chop injuries may be caused by power fans, band saws or ship or airplane propellers, producing extensive soft-tissue laceration or amputation.
Stab-wound mechanism
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A stab wound results when force acts along the long axis of a narrow or pointed object into the body.
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The wound is deeper than its surface length and width. It may result from driving the object into the body or from the body pressing or falling against the object.
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Common stabbing instruments include kitchen knives, sheath knives and penknives.
Types and entry–exit features
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Puncture wounds involve soft tissues. Penetrating wounds enter a body cavity or viscus.
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Perforating wounds pass through the body, with entry on one side and exit on the other.
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The entry wound is larger with inverted edges; the exit is smaller with everted edges because the blade tapers.
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A fatal penetrating injury may produce no signs or symptoms for many hours.
Margins and hilt marks
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Stab-wound edges are usually clean-cut and inverted. Margins may be everted over fatty areas such as a protuberant abdomen or the gluteal region.
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Abrasion and bruising are usually absent, but full penetration may cause the hilt-guard to strike the skin and produce a hilt mark.
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A blunt cutting edge may produce abraded, ragged margins. A knife striking at a right angle produces a symmetrical mark.