Chapter 3 Mechanical Injury

Chapter 3 Mechanical Injury

Section 1 Brief Introduction to Mechanical Injury

Injury is a response of human body to external stimula

ting factors including mechanical, electrical, heat, light and

radioactive factors. Injury may cover three kinds of damag

es to human body:

Section 1 Brief Introduction to Mechanical Injury

Injury is a response of human body to external stimula

ting factors including mechanical, electrical, heat, light and

radioactive factors. Injury may cover three kinds of damag

es to human body:

disruption of the normal structure of tissues, functional disorder and psychological disturbance

disruption of the normal structure of tissues, functional disorder and psychological disturbance

Three factors determining the development of mec

hanical injury:

the nature of the objects or instruments causing the inj

ury

the nature of the affected tissues

the force applied to the body

Three factors determining the development of mec

hanical injury:

the nature of the objects or instruments causing the inj

ury

the nature of the affected tissues

the force applied to the body

1. The weapons or instruments causing the injury 1. The weapons or instruments causing the injury

Three kinds of instruments: the sharp instruments, blunt

instruments and guns or firearms.

(1) The sharp instruments

The sharp instruments are those pointed or sharp-edged objects, such as knife, ax, dagger and scissors.

(2) The blunt instruments

The blunt instruments are those without point or sharp edge, such as stick or club, the bricks, stone and fist etc.

Three kinds of instruments: the sharp instruments, blunt

instruments and guns or firearms.

(1) The sharp instruments

The sharp instruments are those pointed or sharp-edged objects, such as knife, ax, dagger and scissors.

(2) The blunt instruments

The blunt instruments are those without point or sharp edge, such as stick or club, the bricks, stone and fist etc.

Section 2 The types of mechanical injuriesSection 2 The types of mechanical injuries

1.Abrasion An abrasion is a destruction of the skin which usually involves the superficial layers of the epidermis only.

Abrasion is caused by friction of the skin against some rough on sharp surface resulting in the scraping away of superficial portion of the epidermis.

Abrasions are of medico-legal importance as they indicate that some force has been applied to the body.

Under certain conditions, the features of abrasions may suggest the nature, direction and cause of the force and, possibly, the purpose for which it is applied.

1.Abrasion An abrasion is a destruction of the skin which usually involves the superficial layers of the epidermis only.

Abrasion is caused by friction of the skin against some rough on sharp surface resulting in the scraping away of superficial portion of the epidermis.

Abrasions are of medico-legal importance as they indicate that some force has been applied to the body.

Under certain conditions, the features of abrasions may suggest the nature, direction and cause of the force and, possibly, the purpose for which it is applied.

Abrasions are commonly found on the head and face and over bony prominence caused by blows from blunt instruments and from falls.

Abrasions are often accompanied by other injuries such as bruises, fractures or internal injuries.

They may appear either as crescentic marks or as relatively broad parallel grooves which tail away at their ends as caused by fingernails.

Abrasions may be produced after death when a body is dragged away from the scene of a crime.

It is advisable to cut off the abrasion and conduct the histological examination for determination of the antemortem abrasion.

Abrasions are commonly found on the head and face and over bony prominence caused by blows from blunt instruments and from falls.

Abrasions are often accompanied by other injuries such as bruises, fractures or internal injuries.

They may appear either as crescentic marks or as relatively broad parallel grooves which tail away at their ends as caused by fingernails.

Abrasions may be produced after death when a body is dragged away from the scene of a crime.

It is advisable to cut off the abrasion and conduct the histological examination for determination of the antemortem abrasion.

2. Contusions

Contusions, also called bruises, are injuries

characterized by the effusion of blood into the tissue spaces.

The extent and the degree of bruising depend upon the

amount of force applied to the body, and upon other factors

such as the structure and vascularity of the affected tissues.

Because of many variables, it is impossible to determine

the mount of force from the extent and the degree of bruising.

2. Contusions

Contusions, also called bruises, are injuries

characterized by the effusion of blood into the tissue spaces.

The extent and the degree of bruising depend upon the

amount of force applied to the body, and upon other factors

such as the structure and vascularity of the affected tissues.

Because of many variables, it is impossible to determine

the mount of force from the extent and the degree of bruising.

In certain circumstances, the external pattern of a

bruise may correspond to the form of the object or weapon,

which may be of medico-legal importance and can be used as

an indication for judgement of possible weapon.

When the body is struck by a round stick, linear

parallel bruises separated by apparently normal tissue in the

skin may occur, which is called parallel subcutaneous

hemorrhage.

The colour of bruises changes as the extravasated blood

undergoes hemolysis, which are not constant and cannot be

relied upon as an indication of their age.

In certain circumstances, the external pattern of a

bruise may correspond to the form of the object or weapon,

which may be of medico-legal importance and can be used as

an indication for judgement of possible weapon.

When the body is struck by a round stick, linear

parallel bruises separated by apparently normal tissue in the

skin may occur, which is called parallel subcutaneous

hemorrhage.

The colour of bruises changes as the extravasated blood

undergoes hemolysis, which are not constant and cannot be

relied upon as an indication of their age.

bruises

3. Incised wound

Incised wounds are caused by sharp weapons or

objects such as knives, jagged portions of metal or pieces of

broken glass.

An incised wound is usually linear or spindle in shape.

The walls of the incised wound appear smooth and the

edges of the wound are clean-cut.

There are usually no connecting tissues (bridges of the

tissue) between the walls. The wound is often gaping.

3. Incised wound

Incised wounds are caused by sharp weapons or

objects such as knives, jagged portions of metal or pieces of

broken glass.

An incised wound is usually linear or spindle in shape.

The walls of the incised wound appear smooth and the

edges of the wound are clean-cut.

There are usually no connecting tissues (bridges of the

tissue) between the walls. The wound is often gaping.

Hemorrhage from the incised wound is usually profuse.

Bruising may or may not be present surrounding wound

edges.

The breadth of the cutting edge of a sharp weapon cannot

be determined from the width of the wound.

Incised wounds are commonly seen in cases of assault and

homicide, which are usually multiple.

Defense wounds may be found on the forearms and/or in

the palms of the hands.

Accidental incised wounds are seen in traffic injury.

Hemorrhage from the incised wound is usually profuse.

Bruising may or may not be present surrounding wound

edges.

The breadth of the cutting edge of a sharp weapon cannot

be determined from the width of the wound.

Incised wounds are commonly seen in cases of assault and

homicide, which are usually multiple.

Defense wounds may be found on the forearms and/or in

the palms of the hands.

Accidental incised wounds are seen in traffic injury.

Suicidal incised wounds are commonly seen in region of

the wrists and the neck. Incised wounds are sometimes

self-inflicted for the purpose of ending his or her life or

bring false charges against other persons.

Sometimes, in the cases of suicide, some superficial,

parallel cut wounds are found on the front of the left

forearm, the front and outer side of the thighs and the

side of the neck. Such cut wounds are called tentative

incisions or hesitation marks.

Suicidal incised wounds are commonly seen in region of

the wrists and the neck. Incised wounds are sometimes

self-inflicted for the purpose of ending his or her life or

bring false charges against other persons.

Sometimes, in the cases of suicide, some superficial,

parallel cut wounds are found on the front of the left

forearm, the front and outer side of the thighs and the

side of the neck. Such cut wounds are called tentative

incisions or hesitation marks.

4. Stab wounds Stab wounds are caused by long narrow instruments with pointed end. Stab wounds are described as penetrating when they pierce deeply into tissues and as perforating when they transfix tissues and cause exit wounds.

The shape of stab wounds is usually linear or irregular according to nature of weapons. The depth of a stab wound is greater than length and width.

When a sharp weapon such as a knife has been used, the external wound almost invariably takes the form of a split having two pointed extremities.

4. Stab wounds Stab wounds are caused by long narrow instruments with pointed end. Stab wounds are described as penetrating when they pierce deeply into tissues and as perforating when they transfix tissues and cause exit wounds.

The shape of stab wounds is usually linear or irregular according to nature of weapons. The depth of a stab wound is greater than length and width.

When a sharp weapon such as a knife has been used, the external wound almost invariably takes the form of a split having two pointed extremities.

The external opening of a punctured wound may have a triangular or cruciate shape if it is caused by a weapon such as a triangular file or bayonet, or by a square-sectioned instrument such as a spike.

The dimensions of the external opening of a stab wound may be smaller than the diameter or transverse dimensions of the weapon, as the elastic skin is often stretched during the process of penetration. On the other hand, the opening may be larger in cases where the weapon is withdrawn obliquely after penetration.

The external opening of a punctured wound may have a triangular or cruciate shape if it is caused by a weapon such as a triangular file or bayonet, or by a square-sectioned instrument such as a spike.

The dimensions of the external opening of a stab wound may be smaller than the diameter or transverse dimensions of the weapon, as the elastic skin is often stretched during the process of penetration. On the other hand, the opening may be larger in cases where the weapon is withdrawn obliquely after penetration.

The depth of a punctured wound may be greater than the total length of the penetrating object or weapon due to compression of the tissues during the process of penetration.

A single wound track is usually found in relation to a single external opening in a punctured wound. In certain cases where the weapon is partially withdrawn and then reinserted in another direction, two or more tracks may be found in relation to a single external opening.

The skin surrounding the wound may be bruised by the haft of the weapon when a weapon such as a knife or a dagger is thrust into the tissue with considerable force

The depth of a punctured wound may be greater than the total length of the penetrating object or weapon due to compression of the tissues during the process of penetration.

A single wound track is usually found in relation to a single external opening in a punctured wound. In certain cases where the weapon is partially withdrawn and then reinserted in another direction, two or more tracks may be found in relation to a single external opening.

The skin surrounding the wound may be bruised by the haft of the weapon when a weapon such as a knife or a dagger is thrust into the tissue with considerable force

5. Fracture of the bones

When a force is applied to a bone directly or indirectly and the bone is bent beyond the limits of its elasticity, it fractures.

(1) Fractures of the skull

i. The types of fractures of the skullFissured fracture of the skull Depressed fracture of the skullPenetrated fracture of the skullComminuted fracture of the skull

5. Fracture of the bones

When a force is applied to a bone directly or indirectly and the bone is bent beyond the limits of its elasticity, it fractures.

(1) Fractures of the skull

i. The types of fractures of the skullFissured fracture of the skull Depressed fracture of the skullPenetrated fracture of the skullComminuted fracture of the skull

Fissured fracture of the skull

Fissured fracture of the skull may develop when inner or outer table fractures, or both inner and outer table fracture.

Patterns of fissured fracture may vary with length, width, and direction as well as the number of the lines of a fracture.

Fissured fracture of the skull is an indication of blows striking head. The number of lines of fracture is also an indication of the number and sequence of the blows.

Fissured fracture of the skull

Fissured fracture of the skull may develop when inner or outer table fractures, or both inner and outer table fracture.

Patterns of fissured fracture may vary with length, width, and direction as well as the number of the lines of a fracture.

Fissured fracture of the skull is an indication of blows striking head. The number of lines of fracture is also an indication of the number and sequence of the blows.

Depressed fracture of the skull When greater force is applied to the skull, depressed

fracture of the skull may develop due to fracture of outer table or both outer and inner table.

The shape of such a fracture appears to be in the form of cone, circle or oval.

The fracture lines in a depressed-comminuted fracture tend to run radially from the central point at the apex, and at the periphery the fracture lines tend to run in a circular manner.

Depressed fracture of the skull When greater force is applied to the skull, depressed

fracture of the skull may develop due to fracture of outer table or both outer and inner table.

The shape of such a fracture appears to be in the form of cone, circle or oval.

The fracture lines in a depressed-comminuted fracture tend to run radially from the central point at the apex, and at the periphery the fracture lines tend to run in a circular manner.

Penetrated fracture of the skull When a small object strike the skull at a high speed,

such as a bullet, the skull may be penetrated and penetrated fracture of the skull occurs.

Comminuted fracture of the skull When violent force is applied to the skull, some part of

skull may break into pieces or fragments to form comminuted fracture of the skull.

Comminuted fracture may develop by impact of one blow or repeated blows.

Penetrated fracture of the skull When a small object strike the skull at a high speed,

such as a bullet, the skull may be penetrated and penetrated fracture of the skull occurs.

Comminuted fracture of the skull When violent force is applied to the skull, some part of

skull may break into pieces or fragments to form comminuted fracture of the skull.

Comminuted fracture may develop by impact of one blow or repeated blows.

6. Injuries of the intracranial tissues(1) Intracranial hemorrhage

Injury to the meninges and their related vessels often result in intracranial hemorrhages, including extradural, subdural, subarachnoid or subpial hemorrhages.

i. Extradural hemorrhages

(a) Definition

Extradural or epidural hemorrhages are those that occur between the inner surface of the skull and the outer surface of the dural mater.

6. Injuries of the intracranial tissues(1) Intracranial hemorrhage

Injury to the meninges and their related vessels often result in intracranial hemorrhages, including extradural, subdural, subarachnoid or subpial hemorrhages.

i. Extradural hemorrhages

(a) Definition

Extradural or epidural hemorrhages are those that occur between the inner surface of the skull and the outer surface of the dural mater.

(b) Causes of extradural hemorrhages

Extradural hemorrhages may be resulted from torn

diploic veins or from ruptured venous sinuses or

meningeal vessels.

The most important type of extradural hemorrhage is

caused by the rupture of meningeal vessels, especially the

middle meningeal vessels.

The middle meningeal vessels may be transfixed by a

spicule of bone or they may be lacerated by the edge of a

fracture.

(b) Causes of extradural hemorrhages

Extradural hemorrhages may be resulted from torn

diploic veins or from ruptured venous sinuses or

meningeal vessels.

The most important type of extradural hemorrhage is

caused by the rupture of meningeal vessels, especially the

middle meningeal vessels.

The middle meningeal vessels may be transfixed by a

spicule of bone or they may be lacerated by the edge of a

fracture.

ii. Subdural hemorrhages

(a) Definition Subdural hemorrhages are those that happen between the inner surface of the dura mater and the outer surface of the arachnoid.

(b) Causes of subdural bleeding (hemorrhage)

Subdural hemorrhages may arise from tears in the dural venous sinuses or cortical veins, but the most common cause of the subdural bleeding is the rupture of bridging or communicating veins.

ii. Subdural hemorrhages

(a) Definition Subdural hemorrhages are those that happen between the inner surface of the dura mater and the outer surface of the arachnoid.

(b) Causes of subdural bleeding (hemorrhage)

Subdural hemorrhages may arise from tears in the dural venous sinuses or cortical veins, but the most common cause of the subdural bleeding is the rupture of bridging or communicating veins.

iii. Subarachnoid hemorrhage

Subarachnoid bleeding is the commonest form of traumatic intracranial bleeding which occurs between the arachnoid and the pia mater, and usually arise from the rupture of bridging veins.

In cases where the hemorrhage is the only form of the injury, the possibility of a spontaneous subarachnoid hemorrhage from natural causes must be excluded.

An important cause of spontaneous subarachnoid hemorrhage from natural causes is the rupture of a congenital or berry aneurysm of one of the arteries of Willis circle.

iii. Subarachnoid hemorrhage

Subarachnoid bleeding is the commonest form of traumatic intracranial bleeding which occurs between the arachnoid and the pia mater, and usually arise from the rupture of bridging veins.

In cases where the hemorrhage is the only form of the injury, the possibility of a spontaneous subarachnoid hemorrhage from natural causes must be excluded.

An important cause of spontaneous subarachnoid hemorrhage from natural causes is the rupture of a congenital or berry aneurysm of one of the arteries of Willis circle.

(2) Posttraumatic intracerebral hemorrhage Hemorrhages into the brain arising directly from impacts are called posttraumatic intracerebral hemorrhage.

Posttraumatic intracerebral hemorrhage usually develops near the surface of the brain.

A single deep-seated hemorrhage is usually due to some disease process. Emotional excitement or physical exertion may precipitate an intracerebral hemorrhage in an arteriosclerotic and hypertensive subject.

(2) Posttraumatic intracerebral hemorrhage Hemorrhages into the brain arising directly from impacts are called posttraumatic intracerebral hemorrhage.

Posttraumatic intracerebral hemorrhage usually develops near the surface of the brain.

A single deep-seated hemorrhage is usually due to some disease process. Emotional excitement or physical exertion may precipitate an intracerebral hemorrhage in an arteriosclerotic and hypertensive subject.

Indications which assist in the differentiation of natural hemorrhages from traumatic ones include:

(a) The age of the subject;

(b) The site and the extent of the hemorrhage;

(c) The presence of vascular lesions in the

cerebral vessels;

(d) Signs of cardiac hypertrophy and generalized

arteriosclerosis.

Indications which assist in the differentiation of natural hemorrhages from traumatic ones include:

(a) The age of the subject;

(b) The site and the extent of the hemorrhage;

(c) The presence of vascular lesions in the

cerebral vessels;

(d) Signs of cardiac hypertrophy and generalized

arteriosclerosis.

Delayed posttraumatic cerebral apoplexy In posttraumatic intracerebral bleedings, there is an important pathologic entity named delayed traumatic cerebral apoplexy.

This term was first created by Böllinger in 1891. He observed that, after a posttraumatic interval of days or even weeks, a hemorrhagic effusion was found in the substance. Since then many cases concerning with such a type of cerebral apoplexy have been reported. But the mechanisms of the condition are not well known.

Delayed posttraumatic cerebral apoplexy In posttraumatic intracerebral bleedings, there is an important pathologic entity named delayed traumatic cerebral apoplexy.

This term was first created by Böllinger in 1891. He observed that, after a posttraumatic interval of days or even weeks, a hemorrhagic effusion was found in the substance. Since then many cases concerning with such a type of cerebral apoplexy have been reported. But the mechanisms of the condition are not well known.

(3) Cerebral contusions i. Definition

Cerebral contusions are circumscribed areas of brain tissue destruction which are accompanied by extravasations of blood into the affected tissues.

Contusions are found most commonly in the cortex of the brain, but they occur also in the deeper tissues.

In the cortex contusions are often covered by a narrow zone of intact cerebral tissue, which appear frequently wedge-shaped and are surrounded by numerous petechiae.

(3) Cerebral contusions i. Definition

Cerebral contusions are circumscribed areas of brain tissue destruction which are accompanied by extravasations of blood into the affected tissues.

Contusions are found most commonly in the cortex of the brain, but they occur also in the deeper tissues.

In the cortex contusions are often covered by a narrow zone of intact cerebral tissue, which appear frequently wedge-shaped and are surrounded by numerous petechiae.

ii. The types of cerebral contusions

Three kinds of cerebral contusions: coup, contre-coup and intermediate cerebral contusion.

(a) The coup contusion lies beneath the injuries of

the head at the site of impact.

(b) The contre-coup contusion is found in a

somewhat less compact distribution in the

diametrically opposite area.

(c) The intermediate contusion develops at midline

structures of the brain such as callus, capasula

interna, basal ganglion, and hypothalamus,

by the impact of blow to the top of the head.

ii. The types of cerebral contusions

Three kinds of cerebral contusions: coup, contre-coup and intermediate cerebral contusion.

(a) The coup contusion lies beneath the injuries of

the head at the site of impact.

(b) The contre-coup contusion is found in a

somewhat less compact distribution in the

diametrically opposite area.

(c) The intermediate contusion develops at midline

structures of the brain such as callus, capasula

interna, basal ganglion, and hypothalamus,

by the impact of blow to the top of the head.

(4) Traumatic cerebral edema i. Definition Cerebral edema of trauma-origin is an increase in the fluid content of the perivascular and pericellular spaces of the brain by blow applied to the head. ii. Appearances of the cerebral edema The macroscopic criteria on a diagnosis of generalized edema :A flattening of the cerebral gyri or convolutions with obliteration of the sulci.A herniation of the inner portions of the temporal poles through the tentorial hiatus. Herniation of the cerebellar tonsils through the foramen magnum.

(4) Traumatic cerebral edema i. Definition Cerebral edema of trauma-origin is an increase in the fluid content of the perivascular and pericellular spaces of the brain by blow applied to the head. ii. Appearances of the cerebral edema The macroscopic criteria on a diagnosis of generalized edema :A flattening of the cerebral gyri or convolutions with obliteration of the sulci.A herniation of the inner portions of the temporal poles through the tentorial hiatus. Herniation of the cerebellar tonsils through the foramen magnum.

7. Injuries of the heart

Injuries of the heart include penetrating and non-penetrating ones. In forensic practice, non-penetrating injuries of the heart are of greater forensic interest.

Non- penetrating injuries of the heart may be caused by impact to the chest by blows, fall from height or traffic accidents, which may range from functional disturbance such as cardiac concussion to cardiac structure damage, such as pericardial rupture, cardiac rupture, cardiac contusion, and valvular ruptures. All these injuries can be fatal.

7. Injuries of the heart

Injuries of the heart include penetrating and non-penetrating ones. In forensic practice, non-penetrating injuries of the heart are of greater forensic interest.

Non- penetrating injuries of the heart may be caused by impact to the chest by blows, fall from height or traffic accidents, which may range from functional disturbance such as cardiac concussion to cardiac structure damage, such as pericardial rupture, cardiac rupture, cardiac contusion, and valvular ruptures. All these injuries can be fatal.

Section 3 Firearm Injuries

Firearm injuries can be divided into gunshot wound

s due to penetration of the bullet and explosion wounds c

aused by explosion of ammunition.

Gunshot wounds that are caused by penetration of t

he bullet into the body are called gunshot wounds or ball

istic missile injuries.

In most of the bullet injuries there are usually an en

trance wound, a bullet track in the tissues and an exit w

ound.

Section 3 Firearm Injuries

Firearm injuries can be divided into gunshot wound

s due to penetration of the bullet and explosion wounds c

aused by explosion of ammunition.

Gunshot wounds that are caused by penetration of t

he bullet into the body are called gunshot wounds or ball

istic missile injuries.

In most of the bullet injuries there are usually an en

trance wound, a bullet track in the tissues and an exit w

ound.

i. The classification of gunshot wound according to the firing distance

(a) The contact entrance wound: when the gun is

fired with the barrel closely contacted with the skin.

(b) The near contact entrance wound: when the gun is

fired with the barrel partially contacted with the skin.

(c) The close range entrance wound: when the gun is

fired within 30 cm.

(d) The medium-distance entrance wound: when the gun

is fired within 100 cm.

(e) The distant entrance wound: when the gun is fired

beyond 100 cm.

i. The classification of gunshot wound according to the firing distance

(a) The contact entrance wound: when the gun is

fired with the barrel closely contacted with the skin.

(b) The near contact entrance wound: when the gun is

fired with the barrel partially contacted with the skin.

(c) The close range entrance wound: when the gun is

fired within 30 cm.

(d) The medium-distance entrance wound: when the gun

is fired within 100 cm.

(e) The distant entrance wound: when the gun is fired

beyond 100 cm.

ii. The features of gunshot wounds

(a) Entrance wound of the bullet

The diameter is smaller than the caliber of the bullet, especially when a pistol is discharged beyond range of 15cm or rifle beyond 100cm.

The entrance wound is circular in shape and is surrounded by a narrow zone of desquamation and bruising of the skin known as contusion collar.

At the moment of penetration, the bullet may rub against the inner edge of the entrance wound. The inner edge of the wound may be covered by the dirt on the bullet to form grease collar.

ii. The features of gunshot wounds

(a) Entrance wound of the bullet

The diameter is smaller than the caliber of the bullet, especially when a pistol is discharged beyond range of 15cm or rifle beyond 100cm.

The entrance wound is circular in shape and is surrounded by a narrow zone of desquamation and bruising of the skin known as contusion collar.

At the moment of penetration, the bullet may rub against the inner edge of the entrance wound. The inner edge of the wound may be covered by the dirt on the bullet to form grease collar.

The entrance wound is usually oval when a bullet strikes the skin obliquely.

The entrance wound may be surrounded by blackening due to fired powder and soot deposited around the wound if a pistol is discharged at a range of 15cm and a rifle within a range of 100cm.

When a pistol or rifle is discharged very close to or in contact with the surface of the skin, the gases may pass into the tissues with the bullet and cause considerable laceration of the skin and subcutaneous tissues. Under these conditions the entrance wound has a cruciate appearance.

The entrance wound is usually oval when a bullet strikes the skin obliquely.

The entrance wound may be surrounded by blackening due to fired powder and soot deposited around the wound if a pistol is discharged at a range of 15cm and a rifle within a range of 100cm.

When a pistol or rifle is discharged very close to or in contact with the surface of the skin, the gases may pass into the tissues with the bullet and cause considerable laceration of the skin and subcutaneous tissues. Under these conditions the entrance wound has a cruciate appearance.

At close range there is usually some burning

blackening and tattooing of the skin around the entrance

opening, while the hair in the region of the wounds often

singed.

In contact gunshot wounds, the whole of the

discharge passes into the tissues through the bullet

entrance opening. The burning blackening or soot and

powder deposited are found in the depths of wound.

At close range there is usually some burning

blackening and tattooing of the skin around the entrance

opening, while the hair in the region of the wounds often

singed.

In contact gunshot wounds, the whole of the

discharge passes into the tissues through the bullet

entrance opening. The burning blackening or soot and

powder deposited are found in the depths of wound.

iii. The wound track of the bullet

The path that a bullet penetrates through the tissues in the body is called the wound tract of the bullet. A bullet track is situated between the entrance wound and the exit wound, or between the entrance wound and the site of lodgment of the bullet .

A bullet usually travels through the tissues in a straight line. However, a bullet may be deflected from its course when meets the resistance of the tissues, especially when a bullet strikes the bone.

During its travel through the tissues the bullet may turn, wabble, deform or fragment to cause a considerable damage to the tissues.

iii. The wound track of the bullet

The path that a bullet penetrates through the tissues in the body is called the wound tract of the bullet. A bullet track is situated between the entrance wound and the exit wound, or between the entrance wound and the site of lodgment of the bullet .

A bullet usually travels through the tissues in a straight line. However, a bullet may be deflected from its course when meets the resistance of the tissues, especially when a bullet strikes the bone.

During its travel through the tissues the bullet may turn, wabble, deform or fragment to cause a considerable damage to the tissues.

iv. The exit wound of the bullet

Irregular in shape with its edge everted and torn. Burning blackening and tattooing are not seen in relation to the wound.

Usually larger than entrance wound. But in the case of contact entrance wound, exit wound may be smaller than the entrance wound.

In most of the skull injuries, the bullet passes completely through the skull and as it enters the skull from without, it produces a clean-cut hole in the outer table and a larger hole in the inner table. At its point of exit wound from within, the hole in the outer table is larger than the hole in the inner table.

iv. The exit wound of the bullet

Irregular in shape with its edge everted and torn. Burning blackening and tattooing are not seen in relation to the wound.

Usually larger than entrance wound. But in the case of contact entrance wound, exit wound may be smaller than the entrance wound.

In most of the skull injuries, the bullet passes completely through the skull and as it enters the skull from without, it produces a clean-cut hole in the outer table and a larger hole in the inner table. At its point of exit wound from within, the hole in the outer table is larger than the hole in the inner table.

The track of a bullet through the brain tissues varies greatly.

At long ranges, a bullet at high velocity may pass through the skull in a straight line and produce little damage to the brain tissues away from its immediate track.

Considerable damage may be produced if the bullet is deflected from its course within the skull.

At closer ranges, a high–velocity bullet may produce explosive effects in the brain tissues, which are resulted from the dispersion of the bullet energy through out the brain tissues.

The track of a bullet through the brain tissues varies greatly.

At long ranges, a bullet at high velocity may pass through the skull in a straight line and produce little damage to the brain tissues away from its immediate track.

Considerable damage may be produced if the bullet is deflected from its course within the skull.

At closer ranges, a high–velocity bullet may produce explosive effects in the brain tissues, which are resulted from the dispersion of the bullet energy through out the brain tissues.

END