1. Mechanical injuries Injuries caused by sharp cutting weapons This is what we will see 1. Classification of injuries

2. Injuries caused by sharp cutting objects.

3. Injuries are classified in 3 ways • Simple • Grievious • Mechanical injuries • Due to blunt force • Abrasions • Contusions • Lacerations • Fractures • Dueto sharp force • Incised • Chop • Stab • Firearms • Firearm injury • Blast injury • Thermal injuries • Due to cold • Frost bite • Trench foot • Immersion foot • Due to heat • Burns • Scalds • Chemical injuries • Corrosive acids • Corrosive alkalis • Physical • Electricity • Lightening • X-rays • Radioactive subs. • Explosions • Suicide • Homicide • Accident • Fabricated • Self-inflicted • Defence

4. Our interest is in • Injuries due to sharp cutting weapons • Incised wounds • Chop wounds • Stab wounds

5. Incised wounds • Causes • Characters • Age • Histopathology • Medicolegal importance • Special topic- Wounds by glass

6. Causes • Striking the body with edge of the sharp cutting weapon • By drawing the weapon • By using a weapon like saw where multiple cuts merge into one

7. Characters • Margins: • Clean- cut, well-defined and everted (may be inverted if muscle fibres adhere to skin as in scrotum) • no abrasion or contusion (present if weapon has irregular edge or nicked edge)

8. Characters • Width • Greater than edge of weapon (due to retraction of divided tissues and shaking of blade)

9. Characters • Length • Length > Width • Length > Depth • Length is not related to cutting edge of weapon (as it may be drawn to any distance) depth width

10. Characters • Shape • Usually Spindle shaped • Zig-zag if skin is loose as in axilla • Crescentic if present on convex parts like buttocks

11. Characters • Hemorrhage • More due to cleanly cut vessels • Spurting of artery when cut is characteristic

12. Characters • Direction • Deeper at beginning (head of wound) • Shallow at end (tailing of wound) • Above features help to know the direction of wound Tailing

13. Characters • Beveling cut • If blade enters obliquely • Tissue visible at one margin and other margin is beveled (overhanging or undermined)

14. Age of incised wound Fresh: Hematoma formation 12 hours: Edges are red, swollen and adherent with blood and lymph; leucocytic infiltration 24 hours : A continuous layer of endothelial cells covers the surface; overlying this a crust or scab of dried clot is seen

Histopathology Few minutes: Dilatation of capillaries and margination and emigration of endothelial cells covers the surface; overlying this a crust or scab of dried clot is seen.

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