1. Forensic medicine
Topic 3
Mechanical damages and
their forensic significance.
1. Abrasions. 2. Bruising.
3. Wounds. 4. Fractures.
prepared by Kushikov Kairat
2. The forensic medical doctrine of injuries is a section of
forensic medicine about the patterns of occurrence, research methods
and criteria for forensic assessment of injuries.
In forensic medicine, damage (trauma) is a violation of the
structure and function of the body as a result of the action of one or
more external factors. The actions of external factors can disrupt the
integrity of organs and tissues, both of a living organism and a dead
body. In the first case, the damaging factor violates the function and
anatomical structure, postmortem damage does not violate the
function, because it is lost with death.
3. A damaging factor is an object (a material body capable of
acting mechanically) or a phenomenon (electricity, high and low
temperature, radiant energy, etc.) that has the ability to cause
damage. Damaging factors may have a predominantly local damaging
effect (mechanical factors) or predominantly general (barometric
factors). Most of them have both general and local damaging effects
(thermal, radiation, electrical, chemical factors).Damaging factors are
very diverse, but the list of their traumatic properties is small. They
can be divided into three main groups: physical, chemical, biological.
Physical, in turn, are divided into mechanical (blunt, sharp, firearms),
thermal, electrical, barometric and radiation; biological — microbial,
antigenic, etc.
4. The mechanism of damage formation is the process of interaction of
the damaging factor and the damaged part of the body (or the organism as a
whole). The damaging factor is capable of causing damage only as a result of
contact with tissues in the presence of energy sufficient to destroy biological
structures. The process of interaction is usually limited in time and in practice a
specialist can judge it only by the consequences, which are expressed in
morphological and functional signs of damage, reflecting the properties of a
particular object and the features of a particular mechanism of injury. This
approach allows the investigation to objectively evaluate all versions, to resolve
the issue of the possibility or impossibility of damage under the circumstances
established by the investigation, regardless of expert research.
Shear Torsion Compression Tension Flexion
5. General information about damages
Classification of mechanical damage Damages are designated in
accordance with the damaging factor that caused them: damages from the
action of a mechanical factor are called mechanical, from the action of a
thermal factor — thermal, etc., formed from the action of several damaging
factors — combined.
Electrical Injuries
mechanical injury thermal injury
6. General principles of forensic examination of injuries. A large variety
of factors involved in the process of damage formation determines their
morphological variability. Such diversity requires compliance with
general methodological approaches to the study of damage, including the
following fundamental provisions: objectivity (establishing facts, in
particular medical ones, in exact accordance with reality);concreteness
(mandatory, unambiguous and precise solution of those issues that are
put before the expert by the court, investigation or inquiry);a certain
order of damage description that ensures the completeness of their
morphological properties: localization, shape, size, nature of the edges,
ends, walls and bottom of the damage, the presence and nature of foreign
bodies in the wound, extraneous layers around the damage, etc.;a certain
sequence of application of research methods (initial use of methods that
do not change the primary morphology of the damage, then — methods,
partially and then — completely destroying the damage);the need to
formulate each provision of expert conclusions in an understandable way
for investigators and judges who do not have medical
education;argumentation of each provision of expert conclusions
7. Lifetime and postmortem injuries
In forensic medical practice, there are not only lifetime, but also
postmortem injuries. Postmortem injuries can be accidental and are formed
during the transportation of a corpse, resuscitation, autopsy, as well as caused
by insects or animals. Intentional injuries are inflicted during the
dismemberment of a corpse, imitation of suicide or accident, etc..
Post-mortem injuries by a dog crush injury
with amputation of both the lower limbs
8. Intravital injuries are distinguished by the presence of an
organism's response, the severity of which depends mainly on the time
elapsed from the injury to death and the reactivity of the organism.
Signs of lifetime damage are divided into 3 main groups:
macroscopic signs;
microscopic signs;
private signs.
Death Due to Decapitation
9. Determination of lifetime by macroscopic signs
Signs of lifetime caused by activity:• circulatory system:
− traces of external bleeding (blood accumulations, streaks, splashes);
− internal (abdominal) bleeding;
− bleeding into the walls of the wound canal with the formation of a blood
clot, due to the loss of fibrin;
− hemorrhages at a distance from the place of application of force due to
stretching of tissues (when moving) — in the intermuscular spaces and
under the fascia of muscles, in the places of attachment of ligaments, in
lymph nodes;
− the presence of blood in the gallbladder and bladder with damage to the
liver and kidneys, in the ventricles of the brain;
− anemia of the corpse and Minakov's spots with massive blood loss;
− air embolism in case of venous damage;
− tissue embolism of the right half of the heart and branches of the
pulmonary artery;
− the presence of soot on the intima of the aorta (in case of fires);
10. Minakov's spots in forensic medicine are band—shaped
hemorrhages under the endocardium of the left ventricle of the heart,
which are formed in humans with acute blood loss.
11. Determination of lifetime by macroscopic signs
respiratory system:
− aspiration of blood for neck wounds, fractures of the base of the skull,
bones of the nose;
− aspiration of soot and burns of the respiratory tract (in case of fires);
− subcutaneous emphysema, hemopneumothorax with lung and
parietal pleura injuries;
− air embolism with damage to the veins in the neck;
digestive system:
− the presence of blood in the esophagus, stomach, intestines;
− the presence of foreign bodies and parts of injured tissues in the
stomach;
− the presence of soot in the esophagus and stomach (in case of fires).
13. Signs of lifetime caused by:
vascular tissue reaction, which in wound inflammation proceeds in three
phases:
− vasoconstriction phase, lasts from a few seconds to 5 minutes and is
expressed in vascular spasm;
− the phase of early dilation, reaches a maximum after 10 minutes and is
characterized by vascular permeability to plasma proteins;
− the phase of late dilation, lasts several hours, is characterized by
capillary fullness of vascular plexuses of the dermis, subcutaneous fat and
muscle.
14. Determination of the limitation of damages.
Determining the prescription of damage is an expert task not only
when examining a dead body.
There is not only a need to determine the time of injury in living
people, but also methods that allow this to be done (biopsy of
excised tissues, thermography, a complex of X-ray methods, etc.).
In order to reliably determine the time of injury, a comprehensive
study involving various methods is necessary.
15. Blunt force trauma.
Blunt objects include objects that lack sharp edges or ends. Blunt
objects vary in size, shape, relief, mass and hardness.
The place of application and the direction of the acting force are
different, the impact options are: impact, compression, stretching,
friction.Blunt objects cause damage by mechanical action of their surface,
the properties of which are the basis of classification: blunt objects with a
wide flat impact surface (a surface whose area is larger than the contact
zone with the body) and a limited surface (commensurate with the contact
zone with the body, its edges can be displayed in the features of damage)
are distinguished.The damaging factor is a blunt impact that causes
deformation and rupture.
There are compression, shear and separation deformations.From the
action of a blunt object, all kinds of mechanical damage are formed:
abrasions, bruises, wounds, fractures, etc. Morphological features allow us
to determine the properties of a traumatic blunt object and the mechanism
of their formation.
16. Soft tissue damage. Abrasions
The mechanism of formation: rupture and detachment of the epidermis.
Signs:exfoliation or absence of the epidermis at the site of
precipitation;traces of bleeding from fresh abrasions or a crust on the
surface of old ones.Forensic significance: the place of application of
force;the direction of the force can be judged by the location of the slip
strips and scratches on the surface of the abrasions:− at the beginning, the
edge of the abrasion is smooth, the bottom is deep;− at the end, the edge of
the abrasion is uneven with patches of detached epidermis and dirt, a
shallow bottom;lifetime of injury:− lifetime abrasions have a red-brown
color or are covered with a crust;− postmortem abrasions are yellow;
lifetime abrasion
Postmortem abrasion
the lifetime ones have a red-brown color or are covered with a crust,
the postmortem abrasion has a yellow color
17. Soft tissue injuries Abrasions
• the prescription of the injury:
• − on the 1st day, the sunken bottom of the parchment density;
• − on the 2nd day, a towering crust above the level of the surrounding
skin;
• − on the 3rd-4th day, the crust peels off at the edges;
• − on the 7th-10th day, the crust disappears;
• − up to 10-15 days, the skin area at the site of the abrasion has a smooth
shiny
18. determination of the shape, relief and size of the traumatic surface, the
number of traumatic effects. If the object acts at a right angle, has a small
size of the striking surface and a clearly limited configuration, then the
path traveled along the surface of the body is small; establishing the
method of causing damage:
− abrasions on the neck are formed when squeezing it with hands, a loop;
− abrasions in the circumference of the mouth and nose when closing
them with your hand;
− abrasions on the thighs of women during forced sexual intercourse or an
attempt to it;
− abrasions on the hands are a sign of struggle, defense, when falling.
The scraping away of the skin is an
abrasion. The direction the body was
traveling when the injury was received
can be determined if the skin is
heaped up on one edge.
19. Bruising
The mechanism of formation: rupture of blood vessels of the
skin and subcutaneous tissue due to impact and compression of tissues
with their impregnation with blood and the formation of a
bloodcoagulation.
Signs: main: purplish-blue, yellowish or greenish color of the skin
or mucous area;
related:− swelling of the tissue;− density;− soreness;− increase in
local temperature;
Forensic value: indicator of lifetime damage;place indicator
power application;sometimes they display the shape and size of the
surface of the traumatic object;
20. Bruising
the indicator of the prescription of the injury:
− on the 1st-3rd day, the bruise has a purplish-blue color, on the
incisions, the bundle of the bruise is dark red, moist, with a sharp border;
− on the 3rd-4th day, the bruise acquires a purplish-blue color with a
yellowish or greenish tinge, the bundle of the bruise becomes drier,
acquires a brown color;
-on the 6th-9th day, the yellowish tint of the bruise turns into greenish,
and greenish into yellowish, the bundle of the bruise becomes
yellowishor greenish, the sharpness of the borders is smoothed, the
color weakens;
-− after 12-14 days or later, the color of the bruise disappears; the area of
tissue occupied by the bruise becomes invisible.
21. A bruise on the victim's stomach is a "negative" palm print
22. Wounds are a violation of the integrity of the entire thickness of
the skin or mucous membrane, and sometimes deeper lying tissues with
penetration into the body cavity. If the wound canal passes through
the entire damaged part of the body and has an exit hole, then a through
wound is formed.
If the wound canal is long enough, but there is no exit wound, then
the wound is called blind.
In cases where the wound canal opens into the body cavity, the
wound is called penetrating.
The forensic classification of wounds is based on the nature of the
damaging object and the mechanism of causing damage.
Distinguish wounds:
1. Caused by hard blunt objects: a) bruised; 15 b) torn; d) bruised and
torn.
2. Caused by sharp objects: a) cut; b) chopped; c) chopped; d) chopped; e)
sawn.
3. Caused by firearms: a) bullet; b) shotgun; c) fragmentation.
25. Bruised wounds
Mechanism of formation: tissue rupture, accompanied by their
crushing and displacement due to stretching caused by compression or impact.
Signs: wavy edges; polymorphic ends; granular surface of the wound;
thin connective tissue bridges between opposite edges of the wound;
precipitated edges or ends of the wound; • bruising in the circumference of the
wound.
Forensic significance: an indicator of the place of application of force;
establishing the shape of the striking surface of a blunt object.
injury prescription index:− determined by the appearance of abrasions
or bruises surrounding the wound;− by the severity of the inflammatory reaction.
torn bruised
wound
26. Damage to the bones of the skeleton. Fractures
Mechanism of formation: rupture of bone tissue from
stretching caused by flexion, compression, shear, twisting, separation.
Signs: deformity of a body part, unusual mobility, bone
fragments in the wound, bleeding, pain.
Types of fractures: closed, open, complete (rupture of all layers
of bone), incomplete (rupture of one layer of bones), cracks, fractures.
Types of fractures of flat bones: linear (curved) cracks,
depressed (perforated, comminuted, terraced).
depressed skull fracture
27. Types of fractures of tubular bones:
linear (curved) cracks, hammered (flattening of the bone), screw,
tear-off, transverse, oblique, longitudinal, comminuted.
Forensic significance:
the fact of injury and the blunt nature of the impact; an
indicator of the place of application of force: direct fractures have signs
of compression and indirect signs of stretching on the surface facing the
place of application of force;
28. Questions
1.Provide a forensic classification of blunt object
injuries.
2. Abrasions. What is their definition,
mechanism of occurrence, forensic significance?
3. Bruises. What are their definition, mechanism
of occurrence, forensic significance?
4. Bruised wounds. What is their definition,
general properties of wounds, forensic
significance?
5. Fractures. What are the types of fractures,
the mechanism of their formation, the forensic
significance?
