Forensic Examination Mechanical Injuries

Z S M UZ S M U
THE DEPARTMENT OF PATHOLOGICAL ANATOMY and FORENSICTHE DEPARTMENT OF PATHOLOGICAL ANATOMY and FORENSIC
MEDICINEMEDICINE

MECHANICAL INJURIESMECHANICAL INJURIES
Forensic-medical examination of mechanical injuriesForensic-medical examination of mechanical injuries
( the injuries from blunt hard objects and sharp objects) is( the injuries from blunt hard objects and sharp objects) is
an important section of forensic-medical traumatology.an important section of forensic-medical traumatology.
Such injuries are the most widespread.Such injuries are the most widespread.
They can inflict in situations of private life, work, sport,They can inflict in situations of private life, work, sport,
traffic accident etc.traffic accident etc.
Action of blunt and sharp objects can inflict death ofAction of blunt and sharp objects can inflict death of
an injured person.an injured person.

Classification :Classification :
I. Mechanical injuries:I. Mechanical injuries:
1) Abrasions. 2) Contusions.1) Abrasions. 2) Contusions.
3)3) Lacerations. 4) Incised wounds. 5) Stab wounds.Lacerations. 4) Incised wounds. 5) Stab wounds.
6)Chop wounds. 7) Fractures. 8) Dismemberment.6)Chop wounds. 7) Fractures. 8) Dismemberment.
Legally, injuries are classified into:Legally, injuries are classified into:
1. Simple, 2. Moderate, 3. Grievous1. Simple, 2. Moderate, 3. Grievous
Mechanical injuries are injuriesMechanical injuries are injuries
produced by physical violence.produced by physical violence.
A wound or injury is a loss ofA wound or injury is a loss of
the natural continuity of any ofthe natural continuity of any of
the tissues of the living body.the tissues of the living body.

DismembermentDismemberment (( railway traumarailway trauma ))

The mechanical injuries appear as a result of actionThe mechanical injuries appear as a result of action
on the body of blunt and sharp objects: hammers, knives,on the body of blunt and sharp objects: hammers, knives,
scissors,scissors,

Axe, rolling-pin, knives, screw-driver, scissors, ironAxe, rolling-pin, knives, screw-driver, scissors, iron

ABRASIONSABRASIONS
An abrasionAn abrasion is a destruction of the skin,is a destruction of the skin,
which usually involveswhich usually involves the superficial layersthe superficial layers
of the epidermis only.of the epidermis only.
They are caused by aThey are caused by a lateral rubbinglateral rubbing actionaction
by a blow, a fall on a rough surface, by beingby a blow, a fall on a rough surface, by being
dragged in a vehicular accident, fingernails,dragged in a vehicular accident, fingernails,
thorns or teeth bite.thorns or teeth bite.

ABRASIONSABRASIONS
Some pressure and movement by agent onSome pressure and movement by agent on
the surface of the skin is essential.the surface of the skin is essential.
If sufficient friction is applied, partial orIf sufficient friction is applied, partial or
complete removal of the epidermis maycomplete removal of the epidermis may
occur, and the superficial layer of dermis isoccur, and the superficial layer of dermis is
damaged.damaged.

ABRASIONSABRASIONS
The rougher surface and the more rapid theThe rougher surface and the more rapid the
movement of the skin over it, the deeper ismovement of the skin over it, the deeper is
the injury.the injury.
The exposed raw surface is covered byThe exposed raw surface is covered by
exudation of lymph and blood, whichexudation of lymph and blood, which
produces a protective covering known asproduces a protective covering known as
a scab or crust.a scab or crust.

ABRASIONSABRASIONS
Abrasions vary in size, depending on theAbrasions vary in size, depending on the
extent of the body surface exposedextent of the body surface exposed
to the abrading force.to the abrading force.

ABRASIONSABRASIONS
They are simple injuries, bleed slightly, healThey are simple injuries, bleed slightly, heal
rapidly without scar formation.rapidly without scar formation.
Large abrasions can cause severe pain andLarge abrasions can cause severe pain and
bleeding.bleeding.
The size, situation, pattern and number ofThe size, situation, pattern and number of
abrasions should be noted.abrasions should be noted.

AGE OF ABRASIONSAGE OF ABRASIONS
The exact age cannot be determined.
Fresh:Fresh: Bright red.Bright red.
12 to 24 hours:12 to 24 hours: Lymph and blood dries up leaving aLymph and blood dries up leaving a
bright scab.bright scab.
2 to 3 days:2 to 3 days: Reddish-brown scab.Reddish-brown scab.
4 to 7 days:4 to 7 days: Epithelium grows and covers defectEpithelium grows and covers defect
under the scab.under the scab.
After 7 days:After 7 days: Scab dries, shrinks and falls off.Scab dries, shrinks and falls off.

ABRASIONSABRASIONS
Medico-legal Importance:Medico-legal Importance:
1) They give an idea about the site of impact and directionThey give an idea about the site of impact and direction
of the force.of the force.
2) They may be the only external sign of a serious internalThey may be the only external sign of a serious internal
injury.injury.
3) Patterned abrasions are helpful in connecting thePatterned abrasions are helpful in connecting the
wounds with the object which produced them.wounds with the object which produced them.
4) The age of the injury can be determined.The age of the injury can be determined.
5)5) In open wounds, dirt, dust, grease or particles of stoneIn open wounds, dirt, dust, grease or particles of stone
or sand are usually present, which may connect the injuriesor sand are usually present, which may connect the injuries
to the scene of crime.to the scene of crime.

ABRASIONSABRASIONS
6)6) Character and manner of injuryCharacter and manner of injury
may be known from itsmay be known from its
distribution:distribution:
a)a) In throttling, crescent-likeIn throttling, crescent-like
abrasions due to fingernails areabrasions due to fingernails are
found on thefound on the neck,neck,
b)b) In smothering, abrasionsIn smothering, abrasions
may be seen around the mouthmay be seen around the mouth
and nose,and nose,

ABRASIONSABRASIONS
c)c) In sexual assault, abrasionsIn sexual assault, abrasions
may be found on the breasts,may be found on the breasts,
genitals, insidegenitals, inside of the thighs andof the thighs and
around the anus,around the anus,
d)d) Abrasions on the face orAbrasions on the face or
body of the assailant indicate abody of the assailant indicate a
struggle,struggle,
e)e) Abrasions on the victimAbrasions on the victim
may show whether the fingernailsmay show whether the fingernails
of the assailant were long,of the assailant were long,
irregular or even broken.irregular or even broken.

CONTUSIONS (BRUISES)CONTUSIONS (BRUISES)
A contusionA contusion is an effusion of blood into theis an effusion of blood into the
tissues, due to the rupture of blood vessels,tissues, due to the rupture of blood vessels,
(venules and arterioles) due to(venules and arterioles) due to bluntblunt violence.violence.
The bruise is usually situated in theThe bruise is usually situated in the
subcutaneous tissuessubcutaneous tissues, often in the, often in the fat layerfat layer..
In contusion, there is a painful swelling andIn contusion, there is a painful swelling and
crushing or tearing of the subcutaneous tissues,crushing or tearing of the subcutaneous tissues,
usually without destruction of the skin.usually without destruction of the skin.

A contusion is usually aA contusion is usually a superficial injurysuperficial injury, but, but
also occurs in deeper structures and viscera.also occurs in deeper structures and viscera.
They are caused by blunt force, such as fist,They are caused by blunt force, such as fist,
stone, stick, whip, boot, etc.stone, stick, whip, boot, etc.

BruisesBruises may be seen in associationmay be seen in association withwith
abrasions orabrasions or lacerations.lacerations.
When a large blood vessel is injured, a tumour-When a large blood vessel is injured, a tumour-
like mass calledlike mass called haematomahaematoma is formed.is formed.
A fresh bruise is usually tender and slightlyA fresh bruise is usually tender and slightly
raised above the surface of the skin,raised above the surface of the skin,
and even a deep-seated bruise shows someand even a deep-seated bruise shows some
swelling when compared with the opposite limb orswelling when compared with the opposite limb or
part of the body.part of the body.

A bruise has lighter colour in the centreA bruise has lighter colour in the centre
because extravasated blood is pushed outwardbecause extravasated blood is pushed outward
by the impact.by the impact.

Size:Size:
BruisesBruises vary in size: from pinheadvary in size: from pinhead
to large collections of bloodto large collections of blood
in the tissues.in the tissues.
The size of a bruise is slightlyThe size of a bruise is slightly
larger than the surfacelarger than the surface
of the agent which caused it,of the agent which caused it,
as blood continues to escapeas blood continues to escape
into the area.into the area.

Size:Size:
As a general rule, the greater the force of violenceAs a general rule, the greater the force of violence
used, the more extensive will be the bruises,used, the more extensive will be the bruises,
but size and shape are modified by the followingbut size and shape are modified by the following
factors:factors:
- Condition and Type
of Tissue
- Age
- Sex
- Color of Skin
- Natural Disease

THE AGE OF BRUISETHE AGE OF BRUISE
A bruiseA bruise heals by destruction and removal of theheals by destruction and removal of the
extravasated blood.extravasated blood.
TheThe haemoglobinhaemoglobin is broken down intois broken down into methaemoglobin,methaemoglobin,
verdochaemochromogen , biliverdinverdochaemochromogen , biliverdin andand bilirubinbilirubin by theby the
action of enzymes.action of enzymes.
The color change starts at the periphery and extends toThe color change starts at the periphery and extends to
the centre.the centre.
Great care should be exercised in giving opinion as toGreat care should be exercised in giving opinion as to
the age of contusions depending on color changes.the age of contusions depending on color changes.
The doctor can only state that the appearance (color) of aThe doctor can only state that the appearance (color) of a
contusion is consistent with its having been caused socontusion is consistent with its having been caused so
many days back.many days back.

THE AGE OF BRUISETHE AGE OF BRUISE
At first: Red.
Few hours to 2 days : Blue.
3th day : Bluish-black to brown .
4 to 6 days : Greenish .
7 to 12 days : Yellow .
2 weeks – 1 month : Normal.

1)1)The degree of violence may be determined fromThe degree of violence may be determined from
their size.their size.
2)2) Patterned bruises may connect the victim and thePatterned bruises may connect the victim and the
object or weapon, e.g., whips, chains, canes,object or weapon, e.g., whips, chains, canes,
ligature, vehicle, etc.ligature, vehicle, etc.
3) The age of the injury can be determined.3) The age of the injury can be determined.
4) In the case of fall, sand, dust, gravel or mud may4) In the case of fall, sand, dust, gravel or mud may
be found on the body.be found on the body.

5) Character and manner of injury may be known5) Character and manner of injury may be known
from its distribution.from its distribution.
a)a) When the arms are grasped, there may beWhen the arms are grasped, there may be 33
oror 44 bruises onbruises on one side andone side and one largerone larger bruise onbruise on
the opposite side, from the fingers and thumbthe opposite side, from the fingers and thumb
respectively, indicating the position of the assailantrespectively, indicating the position of the assailant
in front of or behind the victim,in front of or behind the victim,
b) Bruising of the arms in a victim may indicateb) Bruising of the arms in a victim may indicate
restraint,restraint,

c)c) Bruising of the shoulder-blades indicate firmBruising of the shoulder-blades indicate firm
pressure on the body against the ground or otherpressure on the body against the ground or other
resisting surface,resisting surface,
d) In manual strangulation, the position andd) In manual strangulation, the position and
number of bruises and nail marks may give annumber of bruises and nail marks may give an
indication of the method of attack or the position ofindication of the method of attack or the position of
the assailant,the assailant,
e) Bruising of thigh especially inner aspect,e) Bruising of thigh especially inner aspect,
and of genitalia indicates rape.and of genitalia indicates rape.

LACERATIONSLACERATIONS
Lacerations are tearsLacerations are tears
or splits of skin,or splits of skin,
mucous membrane,mucous membrane,
muscle or internalmuscle or internal
organs produced byorgans produced by
application of bluntapplication of blunt
force to broad areaforce to broad area
of the body, whichof the body, which
crushed or stretchedcrushed or stretched
tissues beyond thetissues beyond the
limits of theirlimits of their
elasticity.elasticity.

LACERATIONSLACERATIONS
They are caused byThey are caused by
blows fromblows from bluntblunt
objectsobjects, by falls on, by falls on
hard surfaces, byhard surfaces, by
machinery, trafficmachinery, traffic
accidents, etc..accidents, etc..
If the blunt forceIf the blunt force
produces extensiveproduces extensive
bruising andbruising and
laceration of deeperlaceration of deeper
tissues it is calledtissues it is called
crushing injury.crushing injury.

TYPES OF THETYPES OF THE LACERATIONSACERATIONS
1)1) Split Lacerations:Split Lacerations:
Splitting occurs by crushingSplitting occurs by crushing
of the skin between two hardof the skin between two hard
objects. Scalp lacerationsobjects. Scalp lacerations
occur due to the tissuesoccur due to the tissues
being crushed between skullbeing crushed between skull
and some hard object, suchand some hard object, such
as the ground or a bluntas the ground or a blunt
instrument.instrument.

The sites are the scalp,The sites are the scalp,
eyebrows, cheek bones, lowereyebrows, cheek bones, lower
jaw, iliac crest, perineumjaw, iliac crest, perineum
and shin.and shin.

2) Stretch Lacerations:2) Stretch Lacerations:
Overstretching of the skin if it is fixed, will causeOverstretching of the skin if it is fixed, will cause
laceration.laceration.
There is localized pressure with pull whichThere is localized pressure with pull which
increases until tearing occurs and produces theincreases until tearing occurs and produces the
“flap”.“flap”.

3) Avulsion :3) Avulsion :
An avulsion is a lacerationAn avulsion is a laceration
produced by sufficient forceproduced by sufficient force
delivered at an acute angle todelivered at an acute angle to
detach (tear off) a portion of adetach (tear off) a portion of a
traumatized surface from itstraumatized surface from its
attachments.attachments.

4) Tears:4) Tears:
Tearing of the skin and tissues can occur fromTearing of the skin and tissues can occur from
impact by or against irregular objects, such asimpact by or against irregular objects, such as
door handle of car. This is another form ofdoor handle of car. This is another form of
overstretchingoverstretching..
5) Cut Lacerations:5) Cut Lacerations:
Cut lacerations may be produced by a heavy sharp-Cut lacerations may be produced by a heavy sharp-
edged instrument.edged instrument.
The object causing a lacerated wound crushes andThe object causing a lacerated wound crushes and
stretches a broad area of skin, which then splitsstretches a broad area of skin, which then splits
in the centre.in the centre.

CHARACTERSCHARACTERS OF THEOF THE LACERATIONSACERATIONS
1)1)MarginsMargins are irregular, ragged and uneven andare irregular, ragged and uneven and
their ends are pointed or blunt, but show minutetheir ends are pointed or blunt, but show minute
tears in the margins.tears in the margins.
2) Bruising is seen either in the skin or the2) Bruising is seen either in the skin or the
subcutaneous tissues around the wound.subcutaneous tissues around the wound.
3) Deeper tissues are unevenly divided with tags of3) Deeper tissues are unevenly divided with tags of
tissue at the bottom of the wound bridgingtissue at the bottom of the wound bridging
across the margin.across the margin. Tissue bridgesTissue bridges consist ofconsist of
nerves, blood vessels and elastic and connectivenerves, blood vessels and elastic and connective
tissue fibres.tissue fibres.
4)4) Hair bulbs are crushed.Hair bulbs are crushed.

CHARACTERSCHARACTERS OF THEOF THE LACERATIONSACERATIONS
5) Hair and epidermal tags may be driven deeply5) Hair and epidermal tags may be driven deeply
into the wound.into the wound.
6) Haemorrhage is6) Haemorrhage is lessless because the arteries arebecause the arteries are
crushed and torn across irregularly, and thuscrushed and torn across irregularly, and thus
retract and the blood clots readily.retract and the blood clots readily.
7) Foreign matter may be found in the wound.7) Foreign matter may be found in the wound.
8) Depth varies according to the thickness of the8) Depth varies according to the thickness of the
soft parts at the site of the injury and degree ofsoft parts at the site of the injury and degree of
force applied.force applied.
9) The shape and size may not correspond with the9) The shape and size may not correspond with the
weapon or object which produced it.weapon or object which produced it.

LACERATIONSACERATIONS
Complications:Complications:
1)1) Laceration of an internal organ may causeLaceration of an internal organ may cause
severe or evensevere or even fatal bleedingfatal bleeding. Multiple. Multiple
lacerations, involving only the skin andlacerations, involving only the skin and
subcutaneous tissue, each causing somesubcutaneous tissue, each causing some
haemorrhage, may combine to causehaemorrhage, may combine to cause shock andshock and
death.death.
2)2) Pulmonary or systemic fat embolismPulmonary or systemic fat embolism may occurmay occur
due to crushing of subcutaneous tissue.due to crushing of subcutaneous tissue.
3)3) InfectionInfection..
..

1)1) The type of laceration may indicate the cause ofThe type of laceration may indicate the cause of
the injury and the shape of the blunt weapon.the injury and the shape of the blunt weapon.
2) Foreign bodies found in the wound may2) Foreign bodies found in the wound may
indicate the circumstances in which the crimeindicate the circumstances in which the crime
has been committed.has been committed.

Circumstances of Injuries:Circumstances of Injuries:
SuicidalSuicidal lacerations are very rare, as they arelacerations are very rare, as they are
painful.painful.
AccidentalAccidental lacerations are usually situated on thelacerations are usually situated on the
exposed parts of the body and mostly on theexposed parts of the body and mostly on the
same side.same side.
In the case of fall on the head, the abraded scalpIn the case of fall on the head, the abraded scalp
surface will be circular and completely surroundssurface will be circular and completely surrounds
the laceration.the laceration.
HomicidalHomicidal wounds are usually seen on the headwounds are usually seen on the head..

INCISED WOUNDSINCISED WOUNDS
An incised wound is a clean cut through the tissues, whichAn incised wound is a clean cut through the tissues, which
is longer than it is deep.is longer than it is deep.
It is produced by the pressure and friction against theIt is produced by the pressure and friction against the
tissue by an object having a sharp-cutting edge, such astissue by an object having a sharp-cutting edge, such as
knife, razor, scalpel, sword, etc.knife, razor, scalpel, sword, etc.

CHARACTERS OF THECHARACTERS OF THE INCISED WOUNDSINCISED WOUNDS
1)1) Margins:Margins:
The margins are clean cut, well-defined and usuallyThe margins are clean cut, well-defined and usually
everted.everted.
The edges may be inverted if a thin layer of muscleThe edges may be inverted if a thin layer of muscle
fibers is adherent to the skin as in the scrotum.fibers is adherent to the skin as in the scrotum.
The edges are free from contusions andThe edges are free from contusions and
abrasions.abrasions.
2) Width:2) Width:
The width is greater than the edge of the weaponThe width is greater than the edge of the weapon
causing it, due to retraction of the dividedcausing it, due to retraction of the divided
tissues.tissues.
3) Length:
The length is greater than its width and depth.The length is greater than its width and depth.

4) Shape:4) Shape:
It is usually spindle-shaped due to greaterIt is usually spindle-shaped due to greater
retraction of the edges in the centre.retraction of the edges in the centre.
5) Haemorrhage:5) Haemorrhage:
As the vessels are cut cleanly, the haemorrhage isAs the vessels are cut cleanly, the haemorrhage is
more. Spurting of blood occurs if an artery is cut.more. Spurting of blood occurs if an artery is cut.

6) Direction:6) Direction:
Incised wounds are deeper at their beginningIncised wounds are deeper at their beginning
because more pressure is exerted on the knife atbecause more pressure is exerted on the knife at
this point.this point.
This is known as theThis is known as the head of the woundhead of the wound..
Towards the end of the cut, the wound becomesTowards the end of the cut, the wound becomes
increasingly shallow, till finally as the knifeincreasingly shallow, till finally as the knife
leaves the tissues the skin alone is cut.leaves the tissues the skin alone is cut.
This is known as theThis is known as the tailing of the woundtailing of the wound, and, and
indicates the direction in which the cut wasindicates the direction in which the cut was
made.made.

AGE OF INCISED WOUNDSAGE OF INCISED WOUNDS
In an uncomplicated wound healing occurs asIn an uncomplicated wound healing occurs as
follows:follows:
Fresh:Fresh: Haematoma formation.Haematoma formation.
12 hours12 hours:: The edges are red, swollen and adherentThe edges are red, swollen and adherent
with blood and lymph; leucocytic infiltration.with blood and lymph; leucocytic infiltration.
24 hours24 hours:: A continuous layer of endothelial cellsA continuous layer of endothelial cells
covers the surface; overlying this a crust or scabcovers the surface; overlying this a crust or scab
of dried clot is seen; vascular buds begin to form.of dried clot is seen; vascular buds begin to form.
36 hours36 hours:: The capillary network is complete; mitoticThe capillary network is complete; mitotic
activity in the basal cells.activity in the basal cells.
..

AGE OF INCISED WOUNDSAGE OF INCISED WOUNDS
48 to 72 hours: Epidermal cells invade the space
where connective tissue finally develops;
the wound is filled with fibroblasts and capillary
buds grow in from the cut surfaces.
Three to five days: Definite fibrils running parallel
to the vessels are seen; vessels show thickening
and obliteration.
One to two weeks: Scar tissue is formed.

1)1) They indicate the nature of weapon (sharp-edged).They indicate the nature of weapon (sharp-edged).
2) They give an idea about the site of impact and direction of the force.2) They give an idea about the site of impact and direction of the force.
4) Position and character of wounds may indicate mode of production,4) Position and character of wounds may indicate mode of production,
i.e., suicide, accident or homicide.i.e., suicide, accident or homicide.

Circumstances of InjuriesCircumstances of Injuries
Suicide:Suicide:
1) They are multiple and1) They are multiple and
parallel or nearly so, in anyparallel or nearly so, in any
one area.one area.
2) They are uniform in depth2) They are uniform in depth
and direction.and direction.
3) They are relatively trivial.3) They are relatively trivial.
4) The fatal wounds are4) The fatal wounds are
present on several limited,present on several limited,
easily reached areas of theeasily reached areas of the
body, such as front of thebody, such as front of the
neck, wrists, groin, andneck, wrists, groin, and
occasionally on the back ofoccasionally on the back of
legs or on chest.legs or on chest.

Homicidal woundsHomicidal wounds of the chest are usually presentof the chest are usually present
over a wider area and are more horizontal.over a wider area and are more horizontal.
They may be directed from below upwards, which isThey may be directed from below upwards, which is
rarely seen in suicidal wounds.rarely seen in suicidal wounds.
Incised wounds situated on the back, or in such aIncised wounds situated on the back, or in such a
position as cannot be easily reached by a suicideposition as cannot be easily reached by a suicide
are homicidal.are homicidal.

Accidental incised woundsAccidental incised wounds may be caused bymay be caused by
falling upon a sharp-cutting weapon held in thefalling upon a sharp-cutting weapon held in the
hand, or upon a sharp-pointed object, or by ahand, or upon a sharp-pointed object, or by a
sharp piece of broken glass.sharp piece of broken glass.
They may be situated anywhere on the body but areThey may be situated anywhere on the body but are
commonly seen about the hands.commonly seen about the hands.

STAB-INCISED WOUNDSSTAB-INCISED WOUNDS
This is wounds, which appear from action of object with theThis is wounds, which appear from action of object with the
sharp end and sharp edge. This object can be with thesharp end and sharp edge. This object can be with the
one-sided bladeone-sided blade oror two-sided blade.two-sided blade. For example, scalpel,For example, scalpel,
kitchen knife, dagger, etc.kitchen knife, dagger, etc.

CHOP WOUNDSCHOP WOUNDS
They are deep gaping wounds caused by a blow with theThey are deep gaping wounds caused by a blow with the
sharp-cutting edge of a fairly heavy weapon, like an axe, asharp-cutting edge of a fairly heavy weapon, like an axe, a
sabre.sabre.
The dimensions of the wound correspond to cross-The dimensions of the wound correspond to cross-
sections of penetrating blade.sections of penetrating blade.

The margins are sharp and may show slight abrasionThe margins are sharp and may show slight abrasion
and bruising with marked destruction of underlying organs.and bruising with marked destruction of underlying organs.
If the edge is blunt, the margins are ragged and braised.If the edge is blunt, the margins are ragged and braised.
Undermining occurs in the direction towards which theUndermining occurs in the direction towards which the
chop is made.chop is made.
When the whole blade strikes the body at the same time,When the whole blade strikes the body at the same time,
the depth may be same throughout the wound.the depth may be same throughout the wound.

Usually the lower end (heel) of the axe strikes the surfaceUsually the lower end (heel) of the axe strikes the surface
first, which produces a deeper wound than the upper (toe)first, which produces a deeper wound than the upper (toe)
end wound.end wound.
The deeper end indicates the position of the assailant.The deeper end indicates the position of the assailant.
Most of these injuries areMost of these injuries are homicidalhomicidal and usually inflictedand usually inflicted
on the head, face, neck, shoulders and extremities.on the head, face, neck, shoulders and extremities.
AccidentalAccidental injuries are caused by power fans, band sawsinjuries are caused by power fans, band saws
or ship propellers, which may lacerate the soft tissuesor ship propellers, which may lacerate the soft tissues
extensively or amputate parts of the body.extensively or amputate parts of the body.
SuicidalSuicidal injuries are rareinjuries are rare..

STAB OR PUNCTURE WOUNDSSTAB OR PUNCTURE WOUNDS
AA stab woundstab wound is produced fromis produced from
penetration by long narrowpenetration by long narrow
instruments with blunt orinstruments with blunt or
pointed ends into the depthspointed ends into the depths
of the body, such as knife,of the body, such as knife,
dagger, nail, needle, spear,dagger, nail, needle, spear,
arrow, screwdriver, etc. that isarrow, screwdriver, etc. that is
deeper than its length anddeeper than its length and
width on skin.width on skin.
This can occur by driving theThis can occur by driving the
object into the body, or fromobject into the body, or from
the body's pressing or fallingthe body's pressing or falling
against the object.against the object.

STAB OR PUNCTURE WOUNDSSTAB OR PUNCTURE WOUNDS
They are called penetrating wounds, when theyThey are called penetrating wounds, when they
enter a cavity of body. When the weapon entersenter a cavity of body. When the weapon enters
the body on one side, and comes out on thethe body on one side, and comes out on the
other side, perforating wounds or through-and-other side, perforating wounds or through-and-
through puncture wounds are produced.through puncture wounds are produced.
The wound of entry is larger with inverted edges,The wound of entry is larger with inverted edges,
and the wound of exit is smaller with evertedand the wound of exit is smaller with everted
edges, due to tapering of blade.edges, due to tapering of blade.

CHARACTERS OF THECHARACTERS OF THE STAB WOUNDSSTAB WOUNDS
1)1) Margins:Margins:
The edges of the wound are clean-cut.The edges of the wound are clean-cut.
There is usually no abrasion or bruising of the margins, butThere is usually no abrasion or bruising of the margins, but
in full penetration of the blade, bruising may be producedin full penetration of the blade, bruising may be produced
by the hilt or hilt-guard striking the skin.by the hilt or hilt-guard striking the skin.
The margins may be abraded, and ragged if the cuttingThe margins may be abraded, and ragged if the cutting
edge is blunt.edge is blunt.
The opening may enlarge by backward, forward or a lateralThe opening may enlarge by backward, forward or a lateral
movement of the weapon.movement of the weapon.
The wound will gape, if a muscle is cut across.The wound will gape, if a muscle is cut across.

2) Length:2) Length:
The length of the wound is slightly less than the width ofThe length of the wound is slightly less than the width of
the weapon up to which it has been driven in, because ofthe weapon up to which it has been driven in, because of
stretching of the skin.stretching of the skin.
For measuring the length of the stab wound, the edges ofFor measuring the length of the stab wound, the edges of
the wound should be brought together.the wound should be brought together.
If the instrument is thrust in, and is then completelyIf the instrument is thrust in, and is then completely
withdrawn with the cutting edge dragging against onewithdrawn with the cutting edge dragging against one
end, the wound would be extended superficially,end, the wound would be extended superficially,
producing a tail.producing a tail.

3) Depth:3) Depth:
The depth (length of track) is greater than the width andThe depth (length of track) is greater than the width and
length of the external injury.length of the external injury.
The depth of a stab wound is usually equal to, or less thanThe depth of a stab wound is usually equal to, or less than
the length of the blade, that is used in producing it.the length of the blade, that is used in producing it.
4) Shape:4) Shape:
The shape of the wound usually corresponds to the weaponThe shape of the wound usually corresponds to the weapon
used, but the shape of the wounds made by the sameused, but the shape of the wounds made by the same
weapon may differ on different parts of the body.weapon may differ on different parts of the body.

5)5) Direction:Direction:
When the knife penetrates at an angle, the woundWhen the knife penetrates at an angle, the wound
will have a beveled margin on one side withwill have a beveled margin on one side with
undermining (undercutting) on the other, so thatundermining (undercutting) on the other, so that
subcutaneous tissue is visible, indicating thesubcutaneous tissue is visible, indicating the
direction from which the knife entered.direction from which the knife entered.
In solid organs like the liver, the track made by theIn solid organs like the liver, the track made by the
weapon is better seen.weapon is better seen.
The principal direction should be noted first andThe principal direction should be noted first and
other next, e.g., backwards and to the right.other next, e.g., backwards and to the right.

MEDICO-LEGAL IMPORTANCE OF THEMEDICO-LEGAL IMPORTANCE OF THE
STABSTAB WOUNDSWOUNDS
1)1)The shape of the wound may indicate the type ofThe shape of the wound may indicate the type of
the weapon which may have caused the injury.the weapon which may have caused the injury.
2)2)If a broken fragment of weapon is found, it willIf a broken fragment of weapon is found, it will
identify the weapon or will connect an accusedidentify the weapon or will connect an accused
person with the crime.person with the crime.
3)3)The depth of the wound will indicate the force ofThe depth of the wound will indicate the force of
penetration.penetration.

MEDICO-LEGAL IMPORTANCE OF THEMEDICO-LEGAL IMPORTANCE OF THE
STABSTAB WOUNDSWOUNDS
4) Direction and dimensions of the wound indicate4) Direction and dimensions of the wound indicate
the relative positions of the assailant and thethe relative positions of the assailant and the
victim.victim.
6) Position, number and direction of wounds may6) Position, number and direction of wounds may
indicate manner of production, i.e., suicide,indicate manner of production, i.e., suicide,
accident, or homicide.accident, or homicide.

MEDICO-LEGAL QUESTIONS ON TRAUMAMEDICO-LEGAL QUESTIONS ON TRAUMA
1)1)Can post-mortem injuries be distinguished fromCan post-mortem injuries be distinguished from
ante-mortem injuries?ante-mortem injuries?
2)2) Can the time of infliction of the wound beCan the time of infliction of the wound be
determined?determined?
3) Which of the several injuries caused death?
4) How long did the victim live, and could he have
carried out voluntary acts after receiving a fatal
injury?
5) What is the relationship of trauma and natural
disease?

Forensic Examination Mechanical Injuries

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