Removal of the superficial (epithelial) layer of skin; 3 types:
1. Scrape or brush
2. Impact
3. Patterned
Dating Abrasions is possible

1. Scab formation
serum, red cells, fibrin, PMNs
three layers of above
progressive infiltration by PMNs
4-6 hrs
12 hrs
18 hrs
2. Epithelial regeneration30-72 hrs
3. Subepithelial granulation or epith hyperplasiaperivasc inflamm and lymphs
hyperplastic epith and keratin formation
5 - 8 days
9-12 days
4. Regresion of epith and gran tissueepithelium thinner and atrophic, definite basement membrane>12 days

Hemorrhage into soft tissue due to rupture of blood vessels by blunt trauma.
Might be larger than object which produced it.
No standard terminology; difficult to date. Yellow> 18 hrs old.
Can occur within the first few hours after death. Hemorrhage into lids after removal of cornea or into sclera after vitreous stick.

Tears in tissue caused by shearing or crushing force. Occur most commonly over bony prominences.
Avulsion: force is at an oblique angle.

Defense wounds: abrasions and contusions on the back of the hand, wrist, forearm and arm. Fractures of forearm in atemp to ward off blunt object.
Antemortem wounds: histamine and serotonin increased in enzyme assays.

Penetrating: large force over a small area (GSW)
Focal: small force to a small area – usually transverse
Crush: large force over large area – comminuded, e.g. bumper fractures
Tension wedge: wedge of bone pointed in direction of impact
Traction fracture: bone pulled apart by opposing forces
Angulation fracture: bone is bent & snaps
Rotational (spiral) fracture: torsional force
Vertical compression fracture: oblique fracture of long bone, T or Y shaped at ends of bone
Angulation and compression fracture – fracture line is curved
Angulation, compression and rotation – oblique.
Healing: In children a callus takes 2 weeks, consolidated in 4-6 wks, 2-3 mos to heal solidly; in adults consolidation takes 3 months, 4-5 months for a femur.

Internal Injuries
Chin-Sternum-Heart Syndrome: parachutists, fall down stairs with cardiac injury due to sternal compression by chin & laceration of chin (1971)
Cardiac tamponade: as little as 150cc can cause death if accumulates rapidly
Aorta: common tears at descending aorta after subclavian takeoff. Traumatic dissections are rare.
Must r/o other causes of dissection (atherosclerosis, syphilis, cystic medial necrosis).
Cardiac conc
Fat embolization
Amount of fat proportional to degree of injury.
Older persons are prone to more massive fat embolization.

Blast Inury: middle ears, lungs, GI tract. Death commonly by air emboli. Lungs hemorrhagic or edematous. Pneumonthorax & hemothorax.

Helicopter Crash: might drop straight down so resulting trauma may resemble a fall rather than traditional airplane crash.