WOUNDS AND INJURIES

Wounds and injuries

DEFINITION

Disruption of the normal structure of tissues caused by the application of force.

Wounds and injuries

Legal definition of a wound

a wound is where the whole skin is broken, the continuity of the skin broken. An abrasion of the surface is not sufficient. Splits of the inside of the mouth are included but not fractures or internal injuries if the overlying skin is intact.

Wounds and injuries

A wound implies a deliberate action

while an injury can be caused accidentally.

Interpretation of injuries

This is the most important part of the forensic examination

The nature of the agent(s) causing the injuries may be identified in general terms

e.g. due to a blunt object or a sharp object. The pattern of the injuries on the body may help in deciding the circumstances

in which the injuries occurred, accident, suicide or homicide.

1.The nature of the wound, ie whether it is a bruise, abrasion or laceration etc

  2.The wound dimensions, eg length, width, depth etc. 3.It is helpful to take a photograph of the wound with an indication of dimension (eg a tape measure placed next to the wound), 4.Measurements to be taken of the wound as it appears first, and then with wound edges drawn together

 

 

Describing injuries

 

 

  5.The position of the wound in relation to fixed anatomical landmarks, eg distance from the midline, below the clavicle etc

  6.The height of the wound from the heel (ie ground level) - this is particularly important in cases where pedestrians have been struck by motor vehicles

Describing injuries

Blunt force injuries

• Abrasions

• Bruises

• Lacerations

Injuries due to sharp or long instruments

• Incised wounds

• Stab wounds

Bruise

• Crushing of tissues

• epidermis uninjured

• connective tissue crushed

• small vessels ruptured and bleed into tissues

• common in young and old, haematological problems

• falls, assaults

•Bruises are caused by blunt trauma / injury to tissues, resulting in damage to blood vessels beneath the surface.

•Blood leaks out ('extravasation') into surrounding tissues from damaged capillaries, venules and arterioles.

•Bruises may be surface bruises, or deeper within tissues or organs.

Bruises/ Contusions

•Unlike abrasions, the characteristics of the object causing a bruise cannot easily be determined, because blood tends to spread out in a diffuse manner from the site of injury, particularly along fascial planes.

•'shifting' of bruises after time. For example, from faace or scalp to neck

•Bruises may also 'appear' after some days due again to the same phenomenon of blood tracking along tissue planes, and pathologists often re-examine a body again to look for such bruising.

Bruises/ Contusions

Intra-dermal bruises, however, provide an exception to this general rule, as they are superficial - lying just under the epidermis. In this case, there may be good correlation between the bruise seen and the characteristics of the causative object e.g. tramline bruises.

Bruises/ Contusions

 

Ecchymoses/ purpura - smaller than a few millimeters

 

petechiae - pinpoint bruises(usually due to venous engorgement, e.g. in asphyxia, or in defects in blood coagulation such as Disseminated Intravascular Coagulation (DIC)).

Senile purpura – flat purple bruises in elderly

Bruises/ Contusions

A blow from an object may give rise to a combination of injuries, such as a bruise with an abrasion etc, and different parts of the body are more susceptible to bruising than others.

For example, the skin over the eyelids bruises easily, whilst the tougher palmar surface or plantar surface rarely bruises, unless severe direct trauma e.g. fall from a height or torture.

Bruises/ Contusions

The positioning of bruising is significant e.g. multiple rows of spherical/ disc shaped bruises may be seen when an attempt is made to strangle someone with bare hands (manual strangulation).

The bruises are caused by the attacker's fingertips pressing into the skin.

Bruises/ Contusions

'Tramline' bruises

Consist of two parallel linear bruises separated by a paler, undamaged section of skin. This type of injury occurs when the skin is struck with a rod shaped object, which squeezes blood from the vessels at the point of inpact, thus emptying them and preventing them from leaking blood. The edges of the wound are stretched, and blood vessels are torn, causing blood to leak into the surrounding tissues. A similar phenomenon is seen when the injury is caused by a hard spherical object, such as a squash ball !

Bruises/ Contusions

Abrasions

• Surface injury• graze or scratch• rough surface striking the body tangentially• crushed epidermis, pressure or imprint

abrasions• examples: ligature mark, fingernail scratches,

tyre marks, ground or gravel injuries e.g. grazed knees

An abrasion is a superficial injury, commonly known as a 'graze' or 'scratch'.

This type of wound damages only the epidermis (uppermost skin layer), and should not therefore bleed.

However, abrasions do usually extend into the dermis causing slight bleeding.

Abrasions

Abrasions are commonly caused by a 'glancing' impact across the surface of the skin,

If the force is directed vertically down onto the skin surface it may be termed a 'crush' injury.

These wounds are seen where an object has struck the skin (eg a kick), or where the injured person has fallen onto a rough surface, such as road.

Abrasions

Abrasions may be 'linear', a 'scratch'

If broader surface is affected, it is called a 'graze' or 'brush abrasion' (eg where a motorcyclist is thrown from their vehicle, and comes into contact with the road surface in a skidding fashion). Such an abrasion often covers a relatively large area of skin, and is often called a 'friction burn’.

Abrasions

If the surface of an abrasion is examined closely, for example with a hand-held magnifying glass, the direction of force can often be determined, from the torn epidermis.

Strands are drawn towards the end of the injury, and are 'heaped up'. The edges of the wound may also be ragged and directed towards the end of the wound.

Abrasions

Of particular importance in the forensic setting is the fact that abrasions can retain much of the surface characteristics of the object that caused the wound.

For example, there may be a patterned abrasion caused by an element of a vehicle involved in a 'hit-and-run' (such as that made by a radiator grill or bumper), and if the abrasion has been fully documented and photographed (with a scale) and the suspected vehicle is subsequently recovered, the two may be matched up.

Abrasions

Lacerations

• Breach in epidermis and dermis• crush injury• common where skin stretched over bone, scalp,

face and shins• margins bruised and abraded• tissues not cleanly divided, tissue ‘bridges’

across base of wound• bleed profusely• falls, kicks and blows from object

These wounds are commonly known as 'gashes, tears or cuts' of the skin.

The skin surface is split or torn following blunt trauma, and the force causes the full thickness of the skin to be damaged.

Lacerations therefore bleed profusely.

Lacerations

Areas of the body that are commonly the site of lacerations are those with underlying bony support, such as above the eyebrows, on the scalp and face, or over the knees etc, whilst they are less common on areas of the body that are softer such as the buttocks.

Contact with motor vehicles may also cause splitting of the skin due to grinding type movements over the surface, the most severe being a ‘degloving’ injury.

Lacerations

Lacerations have ragged wound edges, as they have been torn apart and not neatly incised as in a surgical wound. scalp lacerations sometimes resemble incised wounds when they have been caused by a regular shaped object. If the wound is examined closely the ragged edges can be visualised, along with crushing and bruising of the margins, hairs driven into the tissues and tissue strands crossing the depth of the wound (nerves, fibrous brands, vessels)

 

 

 

Lacerations

Stab wounds

• Caused by long object

• penetrate body

• small surface wound, depth varies

• shape depends on object penetrating

.These are wounds where the depth of injury is greater than the length.

They penetrate more deeply than slash wounds and tend to come into contact with vital organs in the chest and abdomen

Stab wounds are caused most obviously by knives, but are also caused by bayonets and swords, as well as scissors and even blunter instruments such as screwdrivers.

Stab wounds

 

They are usually slit-like

When the object is removed the skin contracts slightly, leaving a wound that is slightly shorter than the blade width.

The centre of the wound often widens.

muscle and skin contracture around the wound often obscures the size of the knife blade

 

the size of the wound depends upon the depth of penetration of the knife, and whether, for example the parallel section of the knife has been reached (ie near to the hilt of the knife)

 

if the blade is 'rocked' in the wound (ie either the assailant moves the knife around, or the victim moves in relation to the knife), the wound is longer than if the knife is inserted in and out rapidly and in the same direction

 

irregular or 'V' shaped wounds arise when the knife is twisted in the wound

 

most knives are single edged, and have a sharp cutting surface whilst the back of the blade is blunt. The wound may be sharp at one end, and blunt at the other. Unfortunately, this is not always the case, as the blunt edge of the knife may split the skin, and resemble a double edged knife wound.

muscle and skin contracture around the wound often obscures the size of the knife blade

 

the size of the wound depends upon the depth of penetration of the knife, and whether, for example the parallel section of the knife has been reached (ie near to the hilt of the knife)

 

if the blade is 'rocked' in the wound (ie either the assailant moves the knife around, or the victim moves in relation to the knife), the wound is longer than if the knife is inserted in and out rapidly and in the same direction

 

irregular or 'V' shaped wounds arise when the knife is twisted in the wound

 

most knives are single edged, and have a sharp cutting surface whilst the back of the blade is blunt. The wound may be sharp at one end, and blunt at the other. Unfortunately, this is not always the case, as the blunt edge of the knife may split the skin, and resemble a double edged knife wound.

muscle and skin contracture around the wound often obscures the size of the knife blade

 

the size of the wound depends upon the depth of penetration of the knife, and whether, for example the parallel section of the knife has been reached (ie near to the hilt of the knife)

 

if the blade is 'rocked' in the wound (ie either the assailant moves the knife around, or the victim moves in relation to the knife), the wound is longer than if the knife is inserted in and out rapidly and in the same direction

 

irregular or 'V' shaped wounds arise when the knife is twisted in the wound

 

most knives are single edged, and have a sharp cutting surface whilst the back of the blade is blunt. The wound may be sharp at one end, and blunt at the other. Unfortunately, this is not always the case, as the blunt edge of the knife may split the skin, and resemble a double edged knife wound.

Stab wounds

Stab Wounds

Incised wound

• Due to sharp instruments

• length greater than depth

• wound margins uninjured

• deep tissues cleanly cut

• e.g. surgeon’s incised wound

Slash Wounds

These are wounds where the length is greater than the depth, eg a slice wound across the skin.

If the wound involves major blood vessels, it can be life threatening, but in general, they are not as serious as stab wounds.

Incised wounds

Other injuries

• Weals

• Glass injuries

• Axe injuries

• Thermal injuries

• Firearm injuries

• Defence injuries

• Self-inflicted injuries

Miscellaneous

• Weals - triple response

• defence injuries - assaults; arms, hands, legs

• self inflicted - haphazard on arms or body in mental disorders

• tentative injuries - suicide attempts; short, shallow wounds on wrists or neck

Age of injuries

• Colour changes in bruises - purple to yellow

• scab formation in abrasions

• scabbing and scarring of laceration

• histological examination of tissues

Bruises change colour over time, because of the degradation of haemoglobin in the blood. However, the timescale of this degradation is not fixed, and it is therefore possible only to give a rough estimation of the age of the bruise. Colour changes are from dark blue or purple to blue, brown, green and yellow

 

 

 

 

 

Bruises change colour due to degradation of haemoglobin Timescale of this degradation is not fixedPossible only to give a rough estimation of the age of the bruise. Colour changes are from dark blue or purple to blue, brown, green and yellowIn general, small bruises on an otherwise fit and healthy person, could pass through the spectrum of colour changes between 72 hours and 1 week. The more extensive, or deep seated the bruise, the longer it will take to dissapear. If a bruise is brown/ green or yellow it is likely that the injury is at least 18 hours oldMarkedly different coloured bruises suggest that they have been caused at different times, and may indicate signs of chronic abuse, such as of an infant etc.

Age of bruises

Death from injuries

• Haemorrhage

• damage to vital structure

• shock

• infection

• pulmonary thromboembolism

• acute tubular necrosis

• fat embolism

The rounded clear holes seen in the small pulmonary arterial branch in this section of lung are characteristic for fat embolism. Fat embolism syndrome more commonly due to trauma with long bone fractures. It can also be seen with extensive soft tissue trauma, burn injuries, severe fatty liver, and very rarely with orthopedic procedures.

An Oil Red O stain demostrates the fat globules within the pulmonary arterioles. The globules stain reddish-orange. The cumulative effect of these gobules throughout the lungs is similar to a large pulmonary embolus, but the onset of dyspnoea is usually 2 to 3 days following the initiating event, such as blunt trauma with bone fractures.

The capillary loops of this glomerulus contain fat globules in a patient with fat embolism syndrome.

With cerebral fat embolism syndrome, there is loss of consciousness. Note the multitude of petechial hemorrhages here, most in white matter. Cerebral oedema and herniation may follow. Few persons with a history of trauma will develop fat embolism

Seen here with Oil red O stain in a peripheral cerebral artery branch are globules of lipid. This is fat embolism syndrome. Treatment is supportive.