Mechanical injuries

1. Forensic Medicine
Dr. Suchita Rawat (MSc, MPhil, PhD)

2. Injuries: Classification and Medicolegal Aspects
Definition
A. Injury (Legal sec 44) BMR is an important concept of Physiology - Body, Mind,
Reputation, Property
CLASSIFICATION
OF INJURIES
Medical Classification
(Mechanical/Thermal/Chemical/Physical
agent/Explosives)
Medicolegal Classification
(Suicidal/Homicidal/Accidental/Self inflicted/Defense/Iatrogenic
injuries)

3. Injuries: Classification and Medicolegal Aspects
CLASSIFICA
TION OF
INJURIES
Legal Classification
(Hurt u/s 319 : BiDI " Bodily pain, Disease, Infirmity
, IPC/Grievous hurt u/s 320, IPC:
1) EMASCULATION
2-3)Permanent privation sight of either eye/ hearing
of either ear
(4) Privation of any member or joint
 (5) Destruction or permanent impairing of the powers
of any member or joint
(6) Permanent disfiguration of the head or face
(7) Fracture or dislocation of a bone or tooth .
(8) 20 Days

4. CAUSES OF DEATHS FROM WOUNDS
A.
Immediate
Causes
B. Remote
Causes
Reflex vagal inhibition
Mechanical injury to a vital organ

5. AGE OF WOUNDS
Enzyme Histochemistry
10 minutes: Calpains,
cathepsins,(protease), serotonin
30 minutes: Histamine
(allergic/anaphylactic)
1 Hour: ATPase and esterase
2 Hour: Aminopeptidase
4 Hours: Acid Phosphatase
8 Hours : Alkaline phosphatase
Immunohistochemistry
5 minutes : P selectin (activated
platelets/endothelial cells)
10-20 minutes : Fibronectin
(glycoprotein)
1 hour : E selectin (inflammation)
1.5 hours :ICAM I (Intracellular
adhesion molecule 1) immunoglobulin
molecules
2 days :Tanascin (pro inflammatory)
3 days :Collagen III,IV,V
5 days: Collagen I

6. ANTEMORTEM VS. POSTMORTEM WOUNDS
*Haemorrhage extent source /spurting/coagulation/wound edges/ inflammation
and repair/Enzyme histochemistry)
Source: Agrawal, A. (2016).

7. Mechanical Injuries :ABRASIONS
Salient features:
Force/Effects: scratch
and graze abrasions or
imprint /Healing no
scarring /Weapons/on a
wet skin/On drying i.e
dark and brown
Source: Agrawal, A. (2016).

8. Types of Abrasions: Scratch abrasions [syn, linear abrasions, scrapes,
scratches] length/width
● How produced?
● Direction? Skin heaping in same direction
Source: Agrawal, A. (2016).

9. Types of Abrasions: GRAZE abrasion [syn, glancing, grinding, scraping or
sliding abrasions]
Source: Agrawal, A. (2016).
Comprise of uneven, longitudinal parallel lines (grooves or furrows) with the
epithelium heaped up at the ends of these lines.

10. Types of Abrasions: Pressure abrasions syn,
crushing or friction abrasions]
small pressure/
longer period of time

11. Types of Abrasions: Impact abrasions
[syn, contact or imprint abrasions]
Large pressure/
shorter period of time
Headlamp rim marks, or
radiator grille marks - in
head-on vehicular collisions

12. Types of Abrasions: Pressure abrasions and Impact abrasions (pressure
and impact abrasions)

13. Age of Abrasions
Fresh –
Bright red
1 day –
Blood and
lymph dries
up. Bright
red scab
forms
2-3 days –
Reddish
brown scab
4-7 days –
Scab
becomes
dark brown
>7days –
Scab dries,
shrinks and
falls off,
leaving
depigmented
area.

14. site colour Exudation
Antemortem Abrasion vs. Postmortem Abrasion
Source: Agrawal, A. (2016).

15. Medico Legal Importance of
Abrasions
Type of offence
Direction of
force
Force of
impact
Foreign
matter
sticking over
abrasions
Weapon
Time of
assault

16. BRUISES (CONTUSIONS): an effusion of blood into the tissues underneath the skin due to rupture of blood vessels
(arterioles, venules and veins). When the effusion of blood is in other tissues and organs (muscles, lung, heart, brain,
spleen, mesentery etc), it is called a contusion
Salient features:
Colour/cause/size/shape
*Factors Modifying Size and Shape (age i.e. children and adults /sex i.e.
female /obesity/color of skin/condition and type of tissue/weapon
Source: Aggrawal, A. (2016).
(a) Petechial hemorrhages – 0.1-2 mm
(b) Ecchymosis – 2-5 mm (c) Bruise –
more than 5 mm.

17. (i) Vascular and loose tissue
(ii) Firm, fibrous, strongly supported tissue
(iii) Good muscle tone
(iv) Resilient areas

18. Patterned Bruising
Source: Aggrawal, A. (2016).

19. Age of Bruise
Mechanism/Rate of healing/Color changes location/
Source: Aggrawal, A. (2016).

20. Antemortem vs. Postmortem
Bruises
*swelling in and around the wound
damage to epithelium
size
extravasation of blood
site
colour changes i.e dull blue for PM

21. Artificial Bruises vs. true bruise
*Cause/site/colour/shape/margins/itching/vesicles/redne
ss and inflammation/contents

22. ML
Importance
Age of bruise
Alcoholics
Decomposition
Distribution of bruises
Child abuse/Restraint signs/Manual strangulation/Rape/Micro-
contusions/Patterned bruises/Six penny bruises:
Manner of production (self inflicted/Homicidal/accidental)
size

23. LACERATIONS:
Lacerations are tears or splits of skin, mucus membrane,
muscle or internal organs, produced by application of blunt
force to the body, which stretches tissues beyond their limits of
elasticity.
● General Characteristics
(Margins irregular, ragged,
uneven /Edges Angular impact
or perpendicular /Depth/Shape
and
size/Gapping/Bruising/Tissue
bridges
Source: Aggrawal, A. (2016).
Source: Aggrawal, A. (2016).

24. Types of Laceration
*CHOP WOUNDS Chop wounds (or slash wounds) are same as cut
lacerations
Tear Laceration Split laceration Stretch
Laceration
Cut laceration Avulsion

26. This Photo by Unknown Author is licensed under CC BY
True incised wound vs. true
lacerated wound
*edges/margins bruise/injuries to by
nerves, tendons/bleeding

27. Age of Lacerations
• Age determination is difficult unless clear signs of healing are
present [eg Fibroblasts, Granulation tissue, Organizing
infiltrate].
AM and PM Lacerations
• Antemortem lacerations would show (1) Bleeding (2) Blood-
staining of margins(3) Bruising (4) Eversion (5) Gaping (6)
Vital reactions. PM lacerations –ve signs
Medicolegal importance
• Age of lacerations/Extraneous material/Manner of
production/Shape of lacerations (patterned Lacerations)

28. INCISED WOUNDS
Salient features: Force/Skips in
pattern/weapons/Characteristics i.e Length, Width, margins,
Shape spindle shaped, Crecent, zigzag, gapping, Direction)
Source: Aggrawal, A. (2016).
Source: Aggrawal, A. (2016).

32. Difference ???????????
1) Site on neck
2) Level from thyroid cartilage
3) Direction
4) Number of wounds
5) Hesitation mark
6) Tailing
7) Weapon
8) Cadaveric spasm
9) Superficial wounds on other body part

34. Age of Incised Wounds
Hematoma
formation
Fresh
•Edges red,
swollen,
adherent with
blood and
lymph
•Leukocytic
infiltration
12
hours
Dried clot in
the form of
crust or scab.
24 h
hours

35. MLI of Incised Wounds
Reconstruction of crime I.E.
(a) the nature of the
weapon – sharp edged
(b) Age of injury and
(c) Direction of force
Manner of injury i.e.
accidental, suicidal or
homicidal
Limitation: Decomposed body,
Body with incised wounds
immersed in water soon after
death
Source: Aggrawal, A. (2016).

36. STAB WOUNDS
● Salient features: How caused i.e.
Punctured wound, Penetrating
wound, Perforating wound (exit &
entry)/
Source: Aggrawal, A. (2016).
Source: Aggrawal, A. (2016).
Source: Aggrawal, A. (2016).
In perforating wounds, wound of
entry is (a) larger (b) has inverted
edges. Exit is (a) smaller [due to
tapering of blade] (b) has everted
edges. In firearm wounds entry is
smaller; exit is larger.

37. Length, Width

38. MLI of Incised Wounds
Concealed puncture wounds: homicidal.
Depth of wound : Force
Direction and dimension of wounds:
relative position of victim and assailant
Manner of production i.e suicidal,
homicidal, accidental
Multiplicity of wounds: revenge
Shape of wound i.e. single and double
edge
Time of attack i.e. age of wound healing

39. Difference (Suicidal/Homicidal/Accidental stab wounds)
*cause/position of wound/grouping i.e. hesitation/number of
wounds/direction/severity/defence wound

40. Difference (incised/lacerated/stab wound)

41. DEFENSE WOUNDS
Salient features:
● 40% seen in homicide
Incidence
● nature of defense wound
● Location : active vs. passive
● defense wound absent ie.
Unconscious, alcohol, victim
demography
● Medicolegal importance i.e.
homicide/sexual assault
Source: Aggrawal, A. (2016).
Source: Aggrawal, A. (2016).

42. THERAPEUTIC WOUNDS
Source: Aggrawal, A. (2016).
Therapeutic or iatrogenic
wounds are wounds
produced by doctors
during treatment (eg.
surgical wounds of chest
and abdomen for drainage
tubes, tracheostomy,
thoracotomy, laparotomy,
cut-open wounds for IV
catheters etc).

43. This Photo by Unknown Author is licensed under CC BY-SA