Anatomy of Wounds

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Anatomy of Wounds
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Definition of a Wound

• (common definition) defined as damage to any part
  of the body due to the application of mechanical
  force.
• (legal definition) usually requires the integrity
  of the body to be breached.
• Other jurisdictions grade wounds not by their
  physical nature, but by the perceived risk to
  health and life. (This can be extremely
  difficult!)

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Mechanism of Wounding

• The intensity of the force that creates the wound
  obeys the usual laws of physics.
• This can be surmised by saying, the force of
  impact varies directly with the mass of the
  weapon and directly with the square of the
  velocity of impact.
• Kinetic Energy (force) (½mass)(velocity2)

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Making sense of physics

• A one pound brick, placed against the skull may
  not cause any damage.
• The same brick thrown with a velocity of 10 m/s
  may smash the skull.
• Another factor to consider is the area that the
  force impacts.

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The Effect of Mechanical Force

• The condition of the tissue impacted also must be
  considered with the injury.
• Effect can cause
• Compression
• Traction
• Torsion
• Tangential (shear)
• Leverage stresses
• But once the effect is known, it is essential for
  pathologist to adequately describe the actual
  wounds (especially for legal purposes).

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Describing Wounds

• It is essential for pathologist to adequately
  describe wounds (especially for legal purposes).
• The most useful classifications of wounds are
• Abrasions grazes or scratches
• Contusions bruises
• Lacerations cuts or tears
• Incised wounds cuts, slashes or stabs

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Anatomy of the Skin
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Abrasions

• Most superficial of wounds
• Typically thought of as one that does not
  penetrate the full thickness of the epidermis
• Bleeding does sometimes occur because of the
  corrugated nature of the dermal papillae.
• Known as scratches.
• Abrasions become leathery shortly after death.

Simple abrasion of the skin caused by an almost
perpendicular impact of the head against the
ground. There is only slight tangential scuffing
though most abrasions have some element of
sideways contact that damages the epidermis.
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Tangential or Brush Abrasions

• Caused by lateral rubbing rather than vertical
  pressure.
• Direction of force can often be noted in the
  wound.

The epidermal tangs raised tend to pile up at the
distal end of the wound.
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Peeling of Epidermal Layer
A linear abrasion or graze, confined to the
upper layers of skin. The tangential direction of
impact of the weapon was from above downwards.
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Crushing Abrasions

• Involve vertical force to the skin
• Often imprints of weapon are left in the skin
• Abrasions are typically depressed unless swelling
  has occurred.
• Bruising under the dermis often is present.

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Fingernail Abrasions

• Important in child abuse cases, sexual assaults,
  and manual strangulation.
• Women are typically associated with these
  abrasions.
• Upper arms are a frequent site for gripping and
  restraint.
• Marks may be superimposed.
• Determining direction may be difficult.

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Fingernail Abrasions
Abrasion in manual strangulation, the area is
more extensive than is usually seen because of
sliding movements of assailants hands. Small
marks are fingernail abrasions.
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Patterned Abrasions

• Patterned injuries occur when the force is
  applied at or near a right angle to the skin
  surface.

Victim struck in the head with a heavy ashtray
leaving an imprint of the embossed concentric
circles molded into the glass.
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Extensive abrasion of the knees and shins of a
drunk who stumbled along furniture before falling
and striking his head and dying from subsequent
injury.
Abrasions found on the head of a swimming pool
attendant found drowned in a shallow pool. The
abrasions matched the tiles lining the pool, so
it was concluded the attended slipped and fell
unconscious into the water and subsequently
drowned.
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• Patterned abrasions from the back edge of a
  serrated knife. Measurements and photographs
  with a scale should always be obtained to assist
  in identification of the weapon.

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Contusions or Bruises

• Often combined with abrasions.
• Pure bruises lie beneath an intact epidermis and
  consist of an extravascular collection of blood
  from damaged blood vessels.

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Intradermal Bruises

• Typically sharp edged bruises that do not
  continue to the adipose tissue.
• Likely to occur when the weapon has alternating
  ridges and grooves as the skin is forced into the
  grooves.

Pattern Intradermal bruise showing shoe print
pattern of rubber soles of shoes on neck and
T-shirt of a homicide victim.
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Kicking and stamping injury to the face. The
nose is bruised from a kick and the patterned
rubber sole of the shoe has imprinted intradermal
bruising on the forehead.
Extensive bruising of the face due to hitting,
kicking and stamping six days earlier. The
victim has multiple fractures of facial bones.
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• Bruising from a beating with a broom handle. The
  parallel lines indicated impression by a square
  or round weapon. The pressure in the center
  compresses the vessels so that they do not bleed.

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• Suction marks in the left breast of a 22 year old
  homicide victim who was killed by manual
  strangulation.
• Suction bruising is common in sexual assault
  cases.

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This is an example of a patterned abrasion of the
abdomen by scraping along a rough sooty and rusty
surface of a metal tank during a fall. The
pattern may give some indication of the nature of
the surface and the direction of the force.
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Blunt trauma to the head can be suggested by
scalp contusions with subgaleal collection of
blood, as shown here. Image contributed by Todd
Grey, MD, University of Utah
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Kicking (resulting in bruising)

• Typically kicks to the torso leave impressions
  that are readily recognizable.
• Most kicks are delivered to victims already lying
  on the ground.
• The major characteristic of most kicking injuries
  is the severity of bruising and underlying damage.

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Lacerations

• The full thickness of the skin must be penetrated
  to be considered a laceration.
• Different from incised wounds because the
  continuity of skin is interrupted by pressure
  rather than cutting.
• Bridging appears across the wound.
• Lacerations usually need underlying bone to act
  as an anvil to tear the skin.

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Lacerations

• A laceration can be distinguished from an incised
  wound by
• bruising or crushed margins
• bridging (presence of tissue strands across
  wound)
• absence of a sharply linear injury
• If laceration is on scalp, hairs will remain
  intact.

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Here is a very superficial laceration of the
forehead. Note that the skin surface is broken.
There are some small tags of skin where the
surface was irregularly torn.
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Laceration of eyebrow with surrounding bruising.
The victim fell from a low cliff onto rocks. The
sea has washed away the original bleeding.
Multiple homicidal lacerations of the scalp. The
unusual shape is difficult to interpret, but they
were caused by a claw hammer
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Homicidal lacerations of the scalp penetrating
the skull. Although some of the injuries
resemble incised wounds, their margins are
crushed, and hairs and tissue strands cross the
injuries.
Laceration caused by flashlight. The skin is
reddish due to burning. The skin on the
shoulders is reddish due to first- and
second-degree burns.
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Why does a laceration sometimes appear to be a
incision?

• When there is a crushing impact of a blunt object
  on skin supported by bone, such as a scalp or
  skull cap, the skin is sandwiched between weapon
  and bone. This causes a lacerated split that has
  bruised margins and bridges of hair and tissue in
  the wound.

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Incised Wounds

• Injuries caused by sharp objects are classified
  as incised wounds, though the nomenclature is
  again confused.
• Often times injuries cause with weapons like axes
  or spikes are classified as incised wounds, when
  in fact they have more properties of lacerations.
• Can be classified further into cuts, slashes,
  stab and puncture wounds.

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Transection of a body into two halves at waist
level. The victim jumped from a high rise and
landed on a fence.
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Incised Wounds

• Here is an incised wound of the skin of the hand.
  An incision has clean, straight edges made by a
  sharp object such as a knife (or in this case a
  rose thorn). Lacerations are produced from a more
  irregular object and appear as irregular broken
  areas.

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Cuts or Slashes

• Classified as this because they are longer than
  they are deep.
• Assailants strike out with a swiping motion
  rather than a thrusting/stabbing motion.
• Common is gang, and bar-room brawls.
• Also commonly seen in cases of suicide on the
  wrists.
• Typically they tend to be deepest at point of
  first insertion and lessen in depth along the
  length.
• Arms and face are common targets for these types
  of wounds.

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A knife slash of the back showing regular
scratches along the margin. This was inflicted
with a Rambo knife, which has deep serrations
along the back edge that have somehow marked the
skin on withdrawal.
Homicidal slash wounds caused by a knife the
length is greater than the depth, unlike stab
wounds. The long tails are due to the knife
rising from the skin, this indicating direction.
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Stab Wounds

• Of major forensic importance because of their
  high prevalence in homicides.
• A stab wound is an incised wound that is deeper
  than it is long.
• Often penetrates the viscera and involves
  internal organs.

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Nature of Stabbing Weapons

• Knives are the weapons most frequently involved
  and their physical characteristics are important
  in shaping the wound.
• When a pathologist examines a knife as a possible
  murder weapon, he must note
• the length, width and thickness of the blade
• whether it is single or double edged
• the degree of taper from the tip to hilt
• the nature of the back edge in a single-edged
  knife
• the face of the hilt guard adjacent to the knife
• any grooving, serration or forking in the knife
• the sharpness of the edge and extreme tip

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Characteristics of Stab Wounds

• The surface and internal appearances of stab
  wound allow the pathologist to offer an opinion
  upon
• The dimensions of the weapon
• The type of weapon
• The taper of the blade
• Movement of the knife in the wound
• The depth of the thrust
• The direction of the thrust
• The amount of force used

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Dimensions of the Weapon

• The dimensions of the weapon come into critical
  importance in cases in which the weapon is
  removed from the scene by the assailant.
• The pathologist predictions can sometimes aide
  the investigators in their search.
• Because of the elastic nature of the skin, one
  must estimate the knife to be somewhat larger
  than the wound is measured in situ.

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Multiple stabs on the back from the same knife,
showing differing shapes and sizes.
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Langer Lines

• Because of the orientation of muscle fibers, the
  stab wound may have much different appearances
  even when the same blade is used.
• These lines are called langer lines.
• Stab wounds made in the direction of the langer
  lines, appear slender and long, those that
  transect line appear wider.

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A stab wound showing a unilateral fish tail split
cause by the blunt back edge of the knife blade.
This is sometimes bilateral due to the tearing of
tissues. The other end of the wound is sharp
because of the sharp edge of the weapon.
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Movement of the Knife in the Wound

• Significant movement may distort wound shape and
  characteristics.
• Rocking can lengthen the wound.
• Pathologist often make predictions based on the
  victim being static, so it is vital to imagine
  the scenario in a dynamic situation.

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Multiple stab wounds showing variation of size
and shape due to movement of the blade and
varying force and direction.
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• Forcible stabbing can indent the body surface so
  that deep structures can be injured and make the
  appearance of the knife larger.

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• Multiple homicidal knife wounds all inflicted
  with the same weapon. This shows the marked
  variation in wound size from the same knife,
  cause by rocking and twisting movements of either
  weapon or victim

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Estimating Force

• Many factors must be considered when estimating
  amount of force required to inflict the wound.
• Skin is tissue most resistant to knife
  penetration.
• Sharpness of knife is most important factor in
  penetration.
• Speed of approach is vital for penetration.
• Stretched skin is easier to penetrate than lax
  skin.
• Knife penetrates skin rapidly.
• Cartridges are easily cut by knife.

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Superimposed stab wounds

• Homicidal stab wounds of the throat and head
  showing the variance of injuries caused by the
  same knife. The wound under the chin is v shaped
  caused by twisting of the weapon. The larger
  wound is consists of multiple thrust super
  imposed over the manubrium.

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• Three wounds from a single stab with a knife,
  which was I place when the body was discovered.
  The knife had entered obliquely through the inner
  side of the right breast, emerged into the
  cleavage and re-entered the mid line. If the
  knife had not been in situ, interpretation could
  have been more difficult.

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• Multiple homicidal stab and incised wounds
  inflicted with various kitchen utensils. Many of
  the weapons were left in place.

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Blunt and Sharp Force Trauma

• The following sequence of images show wounds
  suffered by an individual that was bludgeoned to
  death with both ends of a claw hammer.

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Superficial wound with massive depressed
fractures below the scalp

• Massive laceration to the side of the skull with
  marked depressed fracture below.
• Superficial lacerations created by the sharp
  force of the claw end of the hammer.
• Ring type injuries caused by the blunt end of the
  hammer striking super imposed.

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• Both sharp and blunt force injuries to the upper
  portion of the head and face.
• Bruising, and depressed fractures located all
  around the cranial vault.

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• Sharp force injuries sustained from the claw of
  the hammer.

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• Temporal bone laceration with depressed skull
  fractures as demonstrated in the following images.

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Non Depressed Cranial Fracture due to blunt force
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Non Depressed Cranial Fracture due to blunt force
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Depressed Cranial Fractures from blunt force
trauma
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Depressed Cranial Fractures from blunt force
trauma
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Injury from Scissors

• Often seen in domestic disturbances.
• Shape of the wound will differ based on whether
  the scissor was used open or closed.
• Typically shaped like a Z

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Profiles

• Here we see various profiles made by scissors
  stabbed through the skin. The cross shapes are
  cause by blade screws or rivets the one on the
  right is a full penetration of one bland of an
  open pair of scissors, the other blade impinging
  flat on the skin

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Defensive Wounds

• The natural reaction to any assault is self
  defense, so defensive wounds are common.
• The most obvious are those seen in knife attacks.
• Fingers, wrists, and forearms
• In attacks from blunt objects, bruises are the
  hallmark of defense.
• They are common on the outer side of the forearms
  hands wrists and backs of victims.

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Various defensive incised wounds on wrist and
hands.
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A thought to ponder . . .

• Every pathologist must avoid the cardinal sin of
  over interpretation.

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The End..Test Tomorrow!!