Forensic Aspects of Trauma

Question 1

What is the definition of an injury?

Answer 1

Physical harm or damage to someone’s body caused by accident or attack
Damage to any part of body due to application of mechanical force

Question 2

Describe mechanism of injury

Answer 2

Intensity of the force obeys the usual laws of physics
Force varies directly with mass of the weapon and directly with square of velocity of impact
If force applied over smaller area then greater impact on unit of tissue

Question 3

What can excessive mechanical force cause?

Answer 3

Compression, traction, torsion and tangential (shearing)

Question 4

How is an injury classified?

Answer 4

Appearance or method of causation - abrasion, contusion, laceration, incised wounds, gunshot wounds and burns
Manner - suicidal, accidental and homicidal
Nature - blunt, sharp or explosive

Question 5

What is a contusion?

Answer 5

Bruises - burst blood vessels in the skin

Question 5

Describe blunt force injuries

Answer 5

Caused by impact with blunt object - ground, fist, foot and weapon
Contusion
Abrasions
Lacerations

Question 6

What is an abrasion?

Answer 6

Graze/ scratch - scraping of skin surface

Question 7

What is a laceration?

Answer 7

Cut/ tear - tear/ split of skin due to crushing

Question 8

What are some different types of patterned bruises?

Answer 8

Tramline, finger tip and other patterns which correspond to shape of blunt force (sole of shoe, belt…)

Question 9

What are factors affecting prominence?

Answer 9

Skin pigmentation, depth + location, fat (more fat then easier bruising), age, resilient areas (buttocks and abdomen bruise less) and coagulative disorders

Question 10

Describe sharp force injuries

Answer 10

Injury caused by any weapon with sharp cutting edge - superficial or penetrating
Incised (longer then deep) or stab wounds (deeper than length)

Question 11

What causes an incised wound?

Answer 11

Superficial sharp force injury caused by slashing motion

Question 12

What causes a stab wound?

Answer 12

Penetrating injury resulting from thrusting motion

Question 13

Describe defensive type injuries

Answer 13

Blunt and sharp force
Can be passive or active
Passive if victim raises arms or legs for protection and is sliced
Active if victim tries to grab weapon or attackers hand - sliced shelved incised wounds

Question 14

Describe self inflicted injuries

Answer 14

Commonly sharp force
Site of election is usually wrists, forearms, chest and abdomen
Parallel, multiple and tentative incisions

Question 15

What do the consequences of injury depend on?

Answer 15

Type of mechanical insult
Nature of target tissue
Forces involved
Number of impacts

Question 16

What are types of skull fractures?

Answer 16

Linear, depressed, mosaic, base and transverse

Question 17

Describe volume of blood and the outcome

Answer 17

35ml - symptomatic
40-50ml - clinical deterioration and life threatening
80-100ml - commonly fatal due to increased ICP and herniation
150ml - fatal

Question 18

Describe traumatic subarachnoid haemorrhage

Answer 18

Specific pathological entity
Due to rapid rotational movement of the head - usually from punch to jaw/ upper part of neck
Causes traumatic rupture of vessels at base of brain
Immediately unconscious and in cardiac arrest

Question 19

Describe diffuse brain injury

Answer 19

Diffuse axonal injury - immediate and prolonged coma with no apparent mass lesion or metabolic abnormality
Traumatic axonal injury - pathological and due to trauma
TAI - focal or diffuse

Question 20

Describe post mortem injuries

Answer 20

Clues in lack of vital reaction and parchmentation
Animal predation and insect predation can be seen