1. Blunt-Force Trauma

2. Being hit or hitting into something hard 3 categories: - abrasions - contusions - lacerations

3. Abrasions - when part of epidermis is removed Skin layers – epidermis (outermost) - dermis (middle – denser, blood vessels & nerves) - hypodermis (bottom – fat & connective tissue)

4. Not very deep, heal quickly If living, trauma = reddish-brown If postmortem = yellow, near transparent 3 forms of abrasions – – Brush – Impact – Pattern

5. Brush (aka scrape) - when force is applied parallel to skin - ex. being dragged - skin scraped off in layers - if affect dermis – more blood  scab -Skin – damaged in direction of force; may find gravel, debris, fibers, or glass -Info re: location or cause

6. Impact – - when force is applied perpendicular to skin  skin crushed - often over bony area

7. Patterned – - when imprint is left on skin - caused by intensity of impact and crushing effect of blunt object on skin - imprint may lead to type of weapon

8. Contusions = bruise – broken blood vessels below surface of skin Can be on internal organs also May cause swelling = hematoma If bleeding under dura (outer surface of brain) – brain is compressed = subdural hematoma - quick death

9. Amount of force & tissue type affect severity Patterned contusion – object is imprinted - good evidence If on internal organs, use computerized tomography (CT) to see CTs use X-rays to produce 3D image

10. Most vulnerable to bruising: - children (looser, more delicate skin) - elderly (less supportive tissue underneath) - obese (athletes have firmer muscles to support & protect blood vessels) - alcoholics (suffer from bleeding disorders)

11. Many contusions may lead to death - extensive blood loss, not enough oxygen  shock

12. Lacerations Tear in tissue caused by a sliding or crushing force Extreme force from blunt objects, a fall, or vehicle impacts Marks w/ irregular edges Can be internal or external

13. Defensive Wounds from Blunt Force Abrasions & contusions on hands, wrists, & arms May have trace evidence from weapon Offensive wounds – when perpetrator injures himself during struggle