Blunt-Force Trauma

• Being hit or hitting into something hard• 3 categories:

- abrasions- contusions- lacerations

Abrasions

- when part of epidermis is removed• Skin layers – epidermis (outermost)

- dermis (middle – denser, blood vessels & nerves)

- hypodermis (bottom – fat & connective tissue)

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

• 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

• Impact – - when force is applied perpendicular

to skin skin crushed- often over bony area

• 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

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

• 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

• 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)

• Many contusions may lead to death- extensive blood loss, not enough oxygen shock

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

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