This document discusses mechanical injuries and their classifications. It defines terms like injury, wound, lesion, and trauma. It describes the mechanisms of various types of injuries caused by mechanical force, including bruises, abrasions, lacerations, incisions, and puncture wounds. It provides classifications for mechanical injuries and describes different types of bruises, abrasions, lacerations, incisions, and puncture wounds in detail with examples. Thermal injuries are also briefly discussed including classifications into exposure to heat and cold and their generic and local effects.

1. Department of
agada tantra evam vyavahara ayurveda
(Forensic Medicine &toxicology),
DBHPS’S
Shri C. B. Guttal Ayurvedic Medical College, DHARWAD
BY
Dr. Deepak S. Mummigatti .M. D.( Ay.)
Assistant professor
Mechanical injuries

2. CONTENTS
♣ DEFINATIONS
♣ TYPES OF INJURIES
♣ MECHANISM OF INJURY
♣ CLASSIFICATIONS OF MECHANICAL INJURY
♣ BRUISE, ABRASION, LACERATION, INCISION,
PUNTURE
Dr Deepak S.M., FMT,
SCBGAMC,DWD

3. DEFINATIONS
INJURY: from the latin injuria
(in- not, jus- the law). The term is often used
synonymously with wound but can have a wider use,
including damage to tissues by heat, cold, chemicals,
electricity, radiation, in addition to mechanical force
WOUND: (legal definition): breach of the full
thickness of the skin (or lining of lip). This excludes
abrasions, bruises, internal injuries and fractures!
WOUND: (medical definition): disruption of the
continuity of the tissues produced by
externalmechanical force'
.Dr Deepak S.M., FMT,
SCBGAMC,DWD

4. .
LESION: from the latin laesio (a hurt).
Originally meant injury, now more widely applied to
include '' any area of injury, disease or local
degeneration in a tissue causing a change in its
function or structure'‘
TRAUMA - bodily harm with or without structural
alterations resulting from interaction with
physicochemical agents, imparting energy to tissues.
May cause morphologically apparent damage (wound)
or produce physiological imbalance (eg
reflex cardiac arrest by neural stimulation) and
secondary effects (eg thrombosis, infection,
obstruction of tubular organs)
Dr Deepak S.M., FMT,
SCBGAMC,DWD

5. TYPES OF TRAUMA
Energy may applied to tissues in various forms :
1) Mechanical Force
Blunt force trauma (BFT)
-a moving object (KE) striking the body as in a blow
-the moving body (KE) striking a fixed object or surface as in a fall
BFT causes bruises, abrasions and lacerations
Sharp force: knife tip or edge, broken glass, jagged metal
- applied force is concentrated over a small area, requires little force to
cut tissues
Firearm; high velocity, small mass projectile
2) Thermal energy: heat or cold
3) Electrical energy: flow of current may cause localised burn if
resistance is high
4) Atmospheric Pressure: high or low, in air or water
5) Radiation: particle or radiation
6) Chemical reaction with tissue releasing energy
Dr Deepak S.M., FMT,
SCBGAMC,DWD

6. Mechanical Force may cause,Impact, Angulation, Compression,
Traction, Torsion, Shearing, Acceleration/deceleration
Different tissues have varying properties of
 Elasticity (tendency of stressed material to regain its unstressed
condition
 Plasticity (tendency to remain in stressed condition)
 Viscosity (resistance to change in shape when stressed)
Different tissues therefore have different elastic limits (tolerance
limits or break points) and are vulnerable to different stresses.
Skin has greater elastic limit than underlying fat and blood
vessels making subcutaneous bruising more common than skin
laceration.
e.g. torsion often causes spiral fracture of tibia, soft
tissues undamaged,
Injury occurs when energy applied exceeds the elastic
limits (or tolerance) of the tissues.
Mechanism of injury
Dr Deepak S.M., FMT,
SCBGAMC,DWD

7. Mechanism..... Cont…..
Whether or not injury occurs following the
application of energy, in whatever form, depends
on Physical and Biological factors.
PHYSICAL FACTORS
1) Degree of Force or K.E. applied:
Force = Mass x Acceleration
Kinetic Energy = 1/2 Mass x Velocity2
Energy depends on half the massof weapon or
projectile, but on the square of its velocity.
That is the reason why even a small
bullet with less of weight, shot with a fire
arm in a high velocity, is capable of producing
more grievous injuries
Dr Deepak S.M., FMT,
SCBGAMC,DWD

8. 2) Area over which force is applied:
• - Same force spread over larger area is less likely to
injure at site of impact
• Edge or tip of knife allows a great concentration of force
applied
• Edge of a plank is more damaging than its flat face
Mechanism..... Cont…..
Wooden plank
Edge
Tip
Dr Deepak S.M., FMT,
SCBGAMC,DWD

9. Mechanism..... Cont…..
3) Duration over which force is applied:
• longer duration allows tissues at site of
impact to deform and dissipate the applied
energy
• eg fall onto soft surface (increases
duration and area of impact)
• seat belt stretching slows down the rate
of transfer of kinetic energy to the body
and spreads the area of impact
over the trunk,
(eg.forehead on dash)
Dr Deepak S.M., FMT,
SCBGAMC,DWD

10. 4) Direction of application:
Transfer of kinetic energy from
weapon or projectile is incomplete
with a glancing blow or exiting bullet
(some wounding potential is wasted)
and complete when the weapon or
bullet come to rest on/in the body
Dr Deepak S.M., FMT,
SCBGAMC,DWD

11. BIOLOGICAL FACTORS
1) Mobility of the body part
• Fixed parts absorbs all applied energy.
• Mobile parts are able to transform KE into
movement
2) Anticipation and coordination
• e.g.-boxer rolling with a punch spreads out
the duration of impact, catching a cricket
ball, rolling with a fall
Dr Deepak S.M., FMT,
SCBGAMC,DWD

12. 3) Biomechanical properties of tissue
Different tissues have different
strengths and weaknesses
• - Skin is elastic and more resistant than underlying tissues
(Bruise > Laceration)
• - Blood vessels more resistant to compression than
stretching
• - Bone more resistant to bending than to torsion
• - Hollow or fluid-filled organs sensitive to compression
• - Brain (semi-fluid) more resistant to direct impact than
rotational impact (--> shearing of nerve fibres)
• - Bone and joint may transmit force to a weak point
Dr Deepak S.M., FMT,
SCBGAMC,DWD

13. CLASSIFICATION OF INJURIES
2.Thermal injuries
Strong Acids
Exposure to heat
Inorganic
H2SO4,HCl
1.Mechanical injuries
4.Miscellaneous
a. Electrocution
b.Lightning
c.Radiations
d.Blasts
3.Chemical injuries
Corrosives
Exposure to cold
Generic effect
Hypothermia
Local effect
Frost bite
Trench foot
Immrn. foot
Generic effect
1.Heat stock
2.Heat cramps
3.Heat syncope
Local effect
Burns
Dry heat
Scalds
Moist heat
Strong Bases
Organic
Oxalic
Carbolic
HCN
Hydrates
NaOH,KOH
NH3OH
Carbonates
NaCO3
KCO3
NH2CO3
Dr Deepak S.M., FMT,
SCBGAMC,DWD

14. TYPES OF MECHANICAL INJURY
punctures contusion
incision laceration
abrasion
MECHANICAL INJURY
Scratches or linear
Grazed or sliding
Pressure ab.
Imprint or impact
stab
patterned
Deep
(sphectacal)
superficial
chopped
Puncture
Crushed Y- Shaped
Dr Deepak S.M., FMT,
SCBGAMC,DWD

15. CLASSIFICATION OF
MECHANICAL INJURIES
Bruise
from Old English b rysan- to crush,
Old French bruser-t o break
Syn. Contusion, Ecchymosis
Defn. "escape of blood from ruptured small
vessels (vein, capillaries, arterioles) into
the surrounding tissues" The resulting
discolouration is seen through the
overlying intact skin.
Due to blunt force trauma.
Site, shape, size, severity of bruising
are very variable.
Dr Deepak S.M., FMT,
SCBGAMC,DWD

16. TYPES OF BRUISES/CONTUSIONS
SIMPLE
DEEP (SPHECTACLE)
IMPRINT
Dr Deepak S.M., FMT,
SCBGAMC,DWD

17. BRUISEA/ CONTUSIONS
SPHECTACLE BRUISEA
(DEEP BRUISING)
Typical CONTUSION
Dr Deepak S.M., FMT,
SCBGAMC,DWD

18. 2) Abrasion
From Latin ab- from and radere- to scrape
Syn. Scratch, Graze
Defn. " a portion of the body surface from
which the skin or mucous membrane has been
crushed or removed by rubbing"
A superficial injury, not involving the full
thickness of the skin, i.e. confined to
epidermis/dermis.
Due to
(1) Direct impact: imprint (may reflect pattern
of causative surface) or
(2) Tangential impact: graze or scratch (may
reflect direction of impact)
Always occurs at the site of impact
Dr Deepak S.M., FMT,
SCBGAMC,DWD

19. ABRASIONS
Dr Deepak S.M., FMT,
SCBGAMC,DWD

20. TYPES OF ABRASIONS
LENIER ABRASION
GRASED ABRASION
PRESSURE ABRASION
IMPRINT ABRASION
Dr Deepak S.M., FMT,
SCBGAMC,DWD

21. (3) Laceration
From Latin lacerare- to tear.
Botanical term- irregular edges
Defn. Full thickness tearing of skin
or tissue due to stretching and
crushing by blunt force
Characteristics: Ragged edge,
Associated bruising/abrasion, Tissue
bridges
Provides little specific information
about the causal object
Dr Deepak S.M., FMT,
SCBGAMC,DWD

22. Lacerations
Dr Deepak S.M., FMT,
SCBGAMC,DWD

23. (4) Incised injuries
From Latin incidere- to cut into.
Surgical term incision with scalpel
Defn. Clean division of the full thickness of skin
(or other tissue) by a sharp-edged
instrument.
Characteristics: Clean cut edges, No associated
bruising/abrasion, No tissue bridges.
Incised wound is LONGER THAN IT IS DEEP.
Provides little specific information about the
causal object
Dr Deepak S.M., FMT,
SCBGAMC,DWD

24. Incision
CHOPPED
Dr Deepak S.M., FMT,
SCBGAMC,DWD

25. (5) Penetrating or Puncture Wounds
Defn. Puncture is "a small hole made with a
sharp point"
ITS DEPTH EXCEEDS ITS LENGTH on the
body surface due to
1. a sharp/flat instrument, e.g. knife
(STAB),
2.a sharp/thin, e.g. needle (NEEDLE
PUNCTURE) or
3.a blunt/long/rigid, e.g. wooden stake
(PUNCTURE)
Shape and size of wound often
indicate dimensions of weapon.Dr Deepak S.M., FMT,
SCBGAMC,DWD

26. Penetrating or Puncture Wounds
Dr Deepak S.M., FMT,
SCBGAMC,DWD

27. Sushruta Says
Dr Deepak S.M., FMT,
SCBGAMC,DWD

28. • mÉËUpÉwÉÉ – 1)uÉëhÉ aÉɧÉ
ÌuÉcÉÑhÉåï, uÉëhÉrÉiÉÏÌiÉ uÉëhÉ:
• 2) uÉ×hÉÉåÌiÉ rÉxqÉÉSè ÃRåûÅÌmÉ
uÉëhÉ uÉxiÉÑ lÉ lÉvrÉÌiÉ
• AÉSåWû kÉÉUhÉɨÉxqÉÉSè uÉëhÉ
CirÉÑcrÉiÉå oÉÑkÉæ:
• AÍkɹÉlÉ – iuÉMç
qÉÉÇxÉÍxÉUÉxlÉruÉÎxjÉxÉÎlkÉMüÉå¸qÉqÉÉ
ïhÉÏirɸÉæ uÉëhÉuÉxiÉÔÌlÉ
uÉëhÉ/ uÉëhÉvÉÉåTü
Dr Deepak S.M., FMT,
SCBGAMC,DWD

29. ²Éæ uÉëhÉÉæ pÉuÉiÉ: -
vÉÉUÏU:,AÉaÉliÉѶÉ
………AÉaÉliÉÑUÌmÉ
mÉÑÂwÉmÉvÉÑmÉͤÉurÉÉsÉxÉUÏxÉ×
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ÑüliÉÉkrÉÉrÉÑkÉÉÍpÉbÉÉiÉÌlÉÍqɨÉ:
AÉaÉliÉÑeÉ uÉëhÉ
Dr Deepak S.M., FMT,
SCBGAMC,DWD

30. MüjÉÇ lÉÉlÉÉ ÌuÉkÉ
uÉëhÉÉÌlÉ pÉuÉÎliÉ?
lÉÉlÉÉkÉÉUqÉÑZÉæ:vÉx§ÉælÉÉïlÉÉxj
ÉÉlÉÌlÉmÉÉÌiÉiÉæ:
lÉÉlÉÉÂmÉÉ uÉëhÉÉ rÉå
xrÉÑxiÉåwÉÉÇ uɤrÉÉÍqÉ sɤÉhÉqÉç
Dr Deepak S.M., FMT,
SCBGAMC,DWD

31. lÉÉlÉÉ xuÉÂmÉÉiqÉMü
uÉëhÉÉÌlÉ -
• AÉrÉiÉcÉiÉÑUxÉëÉ¶É §rÉxÉëÉ
qÉhQûÍsÉlÉxiÉjÉÉ
AkÉïcÉlSìèmÉëiÉÏMüvÉÉ
ÌuÉvÉÉsÉÉ:MÑüÌOûsÉÉxiÉjÉÉ
vÉUÉuÉÌlÉqlÉqÉkrÉɶÉ
rÉuÉqÉkrÉxiÉjÉÅmÉUå
LuÉÇmÉëMüÉUÉM×üiÉrÉÉå
pÉuÉlirÉÉaÉliÉuÉÉå uÉëhÉÉ:
• sɤÉhÉ pÉåS -
Dr Deepak S.M., FMT,
SCBGAMC,DWD

32. Refer sushruts samhita
For detailed explenation on
vrana shotha
Dr Deepak S.M., FMT,
SCBGAMC,DWD

33. Thermal Injuries/ Death
Dr Deepak S.M., FMT,
SCBGAMC,DWD

34. Dr Deepak S.M., FMT,
SCBGAMC,DWD
Thermal Injuries/deaths
Deaths resulting from the effects of
systemic or localised exposure to
excessive heat or cold.
Human body has a varied degrees of limit
of tolerance to both heat and cold. If the
temperature exceeds or falls than this
limit, causes local injuries or general
symptoms leading ultimately to death.

35. Thermal injury classifications
Thermal injuries
Exposure to heatExposure to cold
Generic effect
Hypothermia
Local effect
Frost bite
Trench foot
Immrn. foot
Generic effect
1.Heat stock
2.Heat cramps
3.Heat syncope
Local effect
Burns
Dry heat
Scalds
Moist heat
Dr Deepak S.M., FMT,
SCBGAMC,DWD

36. Injuries due to cold
Generic effect - Hypothermia
It is a condition where the oral or the
axillary temperature is less than 35 C.
Body tolerates dry cold better than wet
cold. The ability of hypothalamus is
completely lost below 30 C.
Fat persons and women tolerate cold
better than the lean and men.
Dr Deepak S.M., FMT,
SCBGAMC,DWD

37. Signs and symptoms of generic
effect of severe cold
Ill effects are seen in 3 stages.
i - Feels cold and shivers, temperature falls.
ii - Shivering stops when temperature is at or
below 320C. The victim becomes lethargic,
drowsy and sleepy, gradually falling into stupor
and coma. Slowly the CVS, RS and GI systems
cease from their functions.
iii - If temperature is lowered to 27oC or less,
maintained for 24hrs leads to death due to
failure of vital centers due to anoxia.
Dr Deepak S.M., FMT,
SCBGAMC,DWD

38. Local effects of cold
- Blanching and paleness of skin due to vascular
spasm
- Follows erythema, oedema and swelling due to
later vascular dilatation.
- Paralysis and increased capillary permeability.
- Tissue becomes frozen stiff and necrotic due to
direct effect of cold
OR
Necrosis followes vascular occlusion,
thrombosis, and secondary inflammation.
Dr Deepak S.M., FMT,
SCBGAMC,DWD

39. Conditions of local effects of cold
Trench foot-
Due to prolonged exposure to severs cold
(5-80C) and dampness as in soldiers during
winter warfare especially in trenches.
Immersion Foot-
local part immersed in cold water for
longer period.
Frost bite-
Occurs due to exposure to extreme
cold(-2.5oCor below), Injury occurs
commonly on extremities, nose ears and
face. Injuries presents necrosis with
blister formation and gangrene.
Dr Deepak S.M., FMT,
SCBGAMC,DWD

40. Thermal burns
• flames
• hot liquids
• hot objects
• gases
Exposure to extreme heat
Dr Deepak S.M., FMT,
SCBGAMC,DWD

41. BURNS
What are burns?
Injuries to tissues caused by:
• Temperature
• Friction
• electricity
• radiation
• Chemicals
Tissue involved here may be many
but mostly the skin
Dr Deepak S.M., FMT,
SCBGAMC,DWD

42.  Epidermis
 Dermis
 Hypodermis
Different degrees of burns are
classified on the bases of part of the
skin involved and the tissue underneath.
Dr Deepak S.M., FMT,
SCBGAMC,DWD

43. Friction burns
• rubbing of the skin
• outer layer
• Also called as brush
burn
• Studied as a type of
abrasion
Dr Deepak S.M., FMT,
SCBGAMC,DWD

44. Electrical burns
• accidental electrical
contact
• depend on:
– strength of electrical
current
– duration of contact
• common causes :
workplace injuries
• rare causes: lightning
Dr Deepak S.M., FMT,
SCBGAMC,DWD

45. Radiation burns
• UV light
• X-rays
• sunlamps
• radiation
therapy
Dr Deepak S.M., FMT,
SCBGAMC,DWD

46. Chemical burns
• strong acids
• strong bases
• detergents
• solvents
Dr Deepak S.M., FMT,
SCBGAMC,DWD

47. BURNS AND SCALDS
Extent of heat-induced injury depends on
1. the applied temperature
2. the time for which the heat is applied
3. the ability of the body surface to conduct away
the excess heat.
Five hours at 40°C or 3 seconds at 60°C
will cause a burn.
Heat may be applied by Conduction from solid,
Convection from liquid or gas,
Radiation-absorption of infra-red
Classification of severity (Wilson)
Dr Deepak S.M., FMT,
SCBGAMC,DWD

48. Injuries due to HEAT
Classification
 Classification on the bases of severity (Wilson)
 First degree burn  superficial
 Second degree burn  partial thickness
 Third degree burn  full thickness
 Fourth degree burn subcutaneous tissue, muscles, bones
Scalds (Moist)Burns (Dry)
Dr Deepak S.M., FMT,
SCBGAMC,DWD

49. BURN WOUND ASSESSMENT
• Classified according to depth of injury and
extent of body surface area involved
• Burn wounds differentiated depending on
the level of dermis and subcutaneous tissue
involved
1. superficial (first-degree)
2. deep (second-degree)
3. full thickness (third and fourth degree)
Dr Deepak S.M., FMT,
SCBGAMC,DWD

50. Dr Deepak S.M., FMT,
SCBGAMC,DWD

51. First-degree burns
• epidermal
• Symptoms
example – mild sunburn
erythema & blistering.
Split in epidermis or at epi/derm
junction
painful due to exposure of nerves
no loss of dermis
capillary dilation, swelling and
exudation
blister, surrounded by zone of
hyperaemia. Blister resorbs or bursts.
re-epithelialises, no scarring.
Dr Deepak S.M., FMT,
SCBGAMC,DWD

52. Second-degree burns
• epidermis and part of dermis
• symptoms
destruction of the full thickness of
skin
not painful as nerves destroyed
epidermis coagulated or charred
central necrosis surrounded by zone of
hyperaemia or FDB
central area sloughs, epidermis grows
in from edges and from epidermis in
surviving
dermal structures (sweat, hair follicle)
underlying zone of tissue is precarious,
may necrose if hypoxia or infection
supervene.
scarring centrally. Contractures may
occur
less painful than FDBexample – contact with hot
objects or flame
Dr Deepak S.M., FMT,
SCBGAMC,DWD

53. Second-degree burn
Dr Deepak S.M., FMT,
SCBGAMC,DWD

54. Third-degree burns
• epidermis and entire dermis
• symptoms
destruction of underlying fat, muscle, bone. When application of heat is prolonged the
tissues may be charred, carbonised or completely destroyed. Dead body may show
wide variation in severity from reddening to complete destruction of a body part. Post
mortem burning obscures ante-mortem burns. Blisters will have collapsed with shreds
and sheets of white epidermis over an angry red base.
More severe burn --> stiffened, yellow-brown leathery skin due to partial
carbonisation. PM drying of exuding skin --> parchmented surface. Skin surface often
blackened by soot deposition. Hair 'clubbed' by melting and re-solidifying, or
completely burnt away. Skin may ignite with subcutaneous fat burning as a fuel,
clothes as a wick. Under lying muscle becomes pale, brownish (part-cooked). Max.
effect with prolonged exposure – slow cooked muscle underlying intact skin. Deep
muscle dehydration and denaturation causes PM contracture;
the flexor groups more powerful --> 'pugilistic attitude'.
Intense, prolonged heat may destroy all soft tissues. Even bone may be reduced to
brittle, grey-white splinters.Spurious wounds appear e.g. heat fracture, heat
haematoma (extradural), skin splits.
example – electrical or chemical sources, flames
Dr Deepak S.M., FMT,
SCBGAMC,DWD

55. Third-degree burns
Dr Deepak S.M., FMT,
SCBGAMC,DWD

56. Dr Deepak S.M., FMT,
SCBGAMC,DWD

57. Dr Deepak S.M., FMT,
SCBGAMC,DWD

58. Fourth-degree burns
• epidermis, dermis and underlying tissue
• symptoms
• black skin
• no sensation
• example - flames
Dr Deepak S.M., FMT,
SCBGAMC,DWD

59. RULES OF NINES
• Head & Neck = 9%
• Each upper extremity (Arms) = 9%
• Each lower extremity (Legs) = 18%
• Anterior trunk= 18%
• Posterior trunk = 18%
• Genitalia (perineum) = 1%
Dr Deepak S.M., FMT,
SCBGAMC,DWD

60. Dr Deepak S.M., FMT,
SCBGAMC,DWD

61. Rue of nine / % of burns
Dr Deepak S.M., FMT,
SCBGAMC,DWD

62. Complications
• infection
• peripheral vascular resistance and
hypovolemia
• acute tubular necrosis
– cardiac arrhythmias
– cardiac arrest
Dr Deepak S.M., FMT,
SCBGAMC,DWD

63. Dr Deepak S.M., FMT,
SCBGAMC,DWD

64. • THANK YOU
TRY NOT TO HURT ANYONE
INSTEAD TRY TO HEAL THE
HARMS
Dr Deepak S.M., FMT,
SCBGAMC,DWD