Forensic Aspects of Trauma Flashcards
Injury
- Physical harm or damage to someone’s body caused by an accident or an attack
- Damage to any part of the body due to the application of mechanical force
What forces does the intensity of injury obey?
Laws of physics
- Force varies directly with mass of the ‘weapon’ and directly with square of velocity of impact
- Kinetic energy = ½ mass x velocity^2
How does area over which force acts affect injury severity?
-Force (same mass and velocity) over a smaller area will deliver a greater impact to any given unit of tissue
How do seatbelts work?
Stretching of seatbelt fabric extends time of energy exchange and considerable area of seatbelt surface is preferable to alternative of transferring all kinetic energy via a few cm^2 of the forehead against the windscreen
What can excessive mechanical force cause?
- Compression
- Traction
- Torsion
- Tangential (shearing)
What does resultant damage depend on?
Type of mechanical insult and nature of the target tissue
How can injury be classified?
Appearance or method of causation:
-Abrasion, contusion, laceration, incised wounds, gunshot wounds, burns
Manner of causation:
-Suicidal, accidental, homicidal
Nature of injury:
-Blunt force, sharp force, explosive
How are blunt force injuries caused?
Caused by impact with blunt object (ground, fist, foot, weapon)
Give examples of blunt force injuries.
Contusions (bruises)
-Burst blood vessels in skin
Abrasions (graze, scratch)
-Scraping of skin surface
Lacerations (cut, tear)
-Tear/split of skin due to crushing
Give examples of patterned bruises.
- Tramline bruises
- Finger trip bruises
- Patterns from objects
What factors affect prominence of bruising?
- Skin pigmentation
- Depth and location
- Increased subcutaneous fat
- Young and old
- Resilient area such as buttocks and abdomen bruise less easily
- Areas with underlying bone bruise more easily
- Coagulative disorders (including alcoholics)
What is a sharp force injury?
- Injury caused by any weapon with sharp cutting edge.
- Can be superficial or penetrating
Give examples of sharp force injuries.
- Incised wounds
- Stab wounds
How do incised wounds occur?
Superficial sharp force injury caused by a slashing motion
How do incised appear?
Longer on the skin surface than it is deep
How do stab wounds occur?
Penetrating injury resulting from thrusting motion
How do stab wounds appear?
Wound depth greater than length on the surface
What types of defensive injuries do you get?
Blunt and sharp force
How do passive defensive injuries occur?
Victim raises arms and legs for protection
What types of passive defensive injuries can occur?
Sliced, shelved often with skin flaps over backs of hands and forearms
How do active defensive injuries occur?
Victim tries to grab weapon or attacker hand
What types of active defensive injuries can occur?
Sliced shelved incised wounds on palmer aspect of hands and web spaces between fingers – particularly between thumb and index finger
What sites are usually used for self inflicted injuries?
- Wrists/forearms
- Chest and abdomen
How do self-inflicted injuries usually appear?
- Commonly sharp force
- Parallel, multiple and tentative injuries
- Positioned under clothing
What does consequence of injury depend on?
Type of mechanical insult
-Blunt, sharp, homicide, suicide, accident
Nature of target tissue
-Head, chest, abdomen, fat
Forces involved
-High speed RTC, fall from a height, kicking, stamping, punch
Number of impacts
-Single vs multiple
What can head injuries result in?
- Skull fractures (linear or depressed)
- Subarachnoid, subdural, extradural haemorrhage
When will patients start to show symptoms of brain haemorrhage?
35ml blood loss
How will a patient present with 40-50ml of brain haemorrhage?
- Clinical deterioration
- Life threatening
How will a patient present with 80-100ml of brain haemorrhage?
Commonly fatal due to increased ICP and herniation
How will a patient present with 150ml+ of brain haemorrhage?
Proves fatal
What is usually the cause of extradural haemorrhage?
Rupture of the middle meningeal artery
What is usually the cause of subdural haemorrhage?
Rupture of emissary
What is usually the cause of subarachnoid haemorrhage?
- Contusions of the brain
- Rupture of berry aneurysms
What is a common consequence of subarachnoid haemorrhage?
Traumatic brain injury
How do traumatic subarachnoid haemorrhages occur?
-Due to rapid rotational movement of head, usually as the result of a single punch to jaw/ upper part of neck or side of head
-Sudden unexpected twisting movement
Causes traumatic rupture of vessels at base of brain – most frequently distal portion of intracranial vertebral arteries at point where they cross the dura
-
What does traumatic subarachnoid haemorrhage result in?
Immediate LOC and cardiac arrest
Diffuse axonal injury
- Clinical term
- Immediate and prolonged coma with no apparent mass lesion or metabolic abnormality
Traumatic axonal injury
- Pathological term
- Damaged axons due to trauma
- Focal or diffuse
- Graded 1-3 dependent on severity
What internal damage can blunt force cause?
Falls, RTC, kicks, blows
Ribs
-Multiple fractures, flail chest
Lungs
-Contusions, lacerations including vessels
Heart
-Bruising, laceration, common carotids
Aorta
-Deceleration trauma, rupture
Abdomen
-Bowel tears, mesenteric haemorrhage and laceration, liver and spleen lacerations, haemorrhage
What internal damage can be caused by sharp force injuries?
Stabs
Intercostal vessels, ribs, pneumothorax, haemothorax
Lungs
-Penetration haemorrhage, collapse, through and through
Heart
-Penetration, tamponade, haemothorax
Aorta
-Haemopericardium, haemothorax
Abdomen
-Penetration of bowel, liver, spleen etc. haemorrhage
What injuries can occur during resuscitation attempts?
- Bruising to neck and chest
- Finger mark bruising
- Bruising/laceration of lips and gums
- Damage to teeth
- Sternal and rib fractures
- Pleural cavity haemorrhage
- Laceration of lung
- Heart rupture
- Venepuncture and cannulation
Give examples of other types of injuries.
- Burns
- Firearm injuries
- Explosions
What post- mortem injuries can occur?
- Parchmentation
- Animal predation
- Insect predation
