New Mechanical

MECHANICAL INJURIES INJURY: Any harm whatever illegally caused to any person in BODY, MIND, REPUTATION or PROPERTY. BODY- Hurt, wound MIND- Torture REPUTATION- Defamatory statements. PROPERTY- theft, robbery. HURT- Whoever causes bodily pain, disease or infirmity to any person has said to cause hurt. WOUND: Forcible solution of continuity of skin or mucus membrane.

CLASSIFICATION OF INJURY ON THE BASIS OF CAUSATION 1. MECHANICAL INJURIES:- Caused by mechanical force A. BLUNT FORCE INJURY B. SHARP FORCE INJURY 1. Abrasion 1. Incised wound / chop wound 2. Bruise / contusion 2 Stab wound 3. lacerated wound 4. Fracture or dislocation of bone. 2. THERMAL INJURIES; 3. CHEMICAL INJURIES 4. FIREARM & EXPLOSION INJURIES ( Combination of 1&2)

ON THE BASIS OF EXTENT IN THE BODY: 1. Cutaneous- Abrasion 2. Percutaneous -stab wounds Puncture wound Does not enter cavity

Penetrating enters a cavity without exit from cavity

enters a cavity with exit from cavity

WALL

3. Subcutaneous- bruise, lacerations, incised wounds.

CAVITY

CAVITY

CAVITY WALL

perforating

WALL

GENERAL PRINCIPLE OF WOUND PRODUCTION: -- Kinetic energy is transmitted from one object to another object where one of the object is in stationary phase and another is in mobile phase , or even both may be stationary phase. -- Possibilities: MOBILR STATIONARY Human body object Object Human body Both human body and object None 2 --> Kinetic energy E = MV / 2 where M= mass , V = Velocity.

FACTORS INFLUENCING WOUND PRODUCTION: 1. Nature of offending object: a. Surface- smooth / rough b. Projecting part- pointed / blunt c. Edges – sharp/ blunt d. Composition- Rigid/ elastic e. Size and mass- large/ small and heavy/ light

2. Amount of energy discharged: 2 Kinetic energy= MV / 2, where there is square value of velocity, hence velocity of object is more important than mass. For example, 1. mass =10 & velocity is 10 , E = 1000/2= 500 2. mass=10 & velocity is 20, E= 4000./2=2000 Thus two objects of same weight will produce more energy with increase in velocity. 3. Condition under which impact occurs: If object strikes the body part which can move freely after impact less damage is produced because some portion is utilised in mobilising that part. . Where as if it strikes fixed part, there is no scope of movement and hence all energy is utilised in production of damage. 4. Nature of tissue affected: - Elasticity, composition, underneath tissue, contents of cavity. A.SKIN : - Thich layer / thin layer of epidermis - Mucous covering

B. SUBSUTANEOUS TISSUE/ UNDERNEATH STRUCTURE: More the subcutaneous tissue --> more the cushioning effect--> lees the damage. C.MUSCLES: --Being more elastic can tolerate perpendicular force but force in any other direction will produce more damage as the fiber arrangement is disturbed. -- Muscles in contracted stage show more damage as fires are already stretched leaving little or no scope for further expansion. D. BONES -- Middle unsupported part more vulnerable. -- Ossified part or bone more vulnerable. E. BODY FLUIDS & GASES: - Gas in a cavity offer pneumo static resistance. - Fluid can be displaced but cant be compressed. - PASCA’S LAW- “ Force exerted upon any part of enclosed fluid is transmitted equally in all directions. -Hence same force will produce less damage in empty bladder as compared to bladder full of urine.

ABRASION: Definition: It is a type of mechanical injury resulting in destruction of skin( usually epidermis only) due to friction against a rough surface.

Mechanism of production: Some movement and pressure or friction between body surface and rough causative surface are necessary for its production. Types of abrasion: 1. SCRATCH: -Linear injury caused by sharp objects like thorn, pin, fingernail etc. passing across the skin. -The direction is denoted by heaping up of epidermal tags where it gets terminated. - Fingernails produce crescent shape scratches. 2. GRAZE:- Brush burn/ sliding/ scraping - Caused when body surface scrapes or slides against a broad area with multiple rough projections. - Comprises of multiple uneven almost parallel scratches.

3. Pressure abrasion - Distance between object & body is less - Velocity of either of them is absent/ less - Contact is prolonged - Exampleligature mark in hanging teeth bites

4. Impact abrasion more more transient impression of head lamp rim or any other prominent part of vehicle in RTA

Circumstances in which seen: a. Fall over rough surface. b. Scratching by nail, teeth , c. Rope or ligature material in compression of neck. d. Road traffic accidents.

Age of abrasion: 1. Fresh- red exudate with more lymph 2. 12-24 hrs- brown scab due to drying 3. 2-3 days- reddish brown scab 4. 4-7 days- epithelium starts growing at margins 5. 7-10 days- shrinkage of scab and fall off leaving pale area. 6. 10-12 days- Complete epithelisation without any evidence of abrasion

Difference between Ante mortem 1. Colour- red/ brown 2. Scab - present 3. Fresh- bleeding present 4.Healing- present 5.Location- any body part 6.Surface - moist due to exudation

and

Post mortem abrasion pale yellow brown absent absent absent bony prominences dry

Medico legal Importance: 1.Suggest type of object and direction of impact. 2.Probable sign of internal damage. 3. Age of wound suggest time of injury 4. Foreign material may be present on it – suggests place of injury 5. Location of wound may help in reconstruction of crime.

CONTUSION / BRUISE: Definition: It is extravasation of blood due to rupture of blood vessels caused by blunt force.

Factors influencing causation and appearance : 1. Nature and severity of force- proportionate 2. Vascularity- proportionate 3. Condition and type of tissue-- supporting tissue more & loose like vulva, eyelids,breast, buttocks– more -- Thin skin – ore, thick skin ( sole, palm)- less -- Bone just underneath- more

4. Predisposing factors: -- Age- infant more vulnerable. - Sex- female more vulnerable - Colour of skin- better perceived in fair skinned persons -Disease- Coagulation disorders, Vit. K & prothombin deficiency, scurvy, haemophilia, chronic alcoholics.

Size and shape of bruise - Margins are diffuse and irregular - Shape corresponds to object causingit..i .e fingertip bruising in throttling - PATTERNED BRUISING: Central pale area corresponding to breadth of object object

Two parallel bruises on each side of pale area- “ Rail road pattern” bruise

Ectopic Bruise: Many a times bruise may not appear at site of impact but can appear at any other site. Due to gravity shifting of blood , it flows along the fascial planes or between muscle layers and get accumulated where it becomes superficial or where such plane ends- just above bony margins. Examples 1.Blunt impact on forehead or frontal area f scalp will produce bruise on upper eye lid.. 2. Extra dural hemoorage may cross a fracture in Anterior cranial fossa at base and produce “ Black eye” or “ spectacle hematoma”. - Middle cranial fossa and produce bruise behind external ea. 3.Trauma to jaw may produce bruise at neck 4. Trauma to thigh may produce bruise at knee 5. Trauma to legs may produce bruise at ankles.

Delayed bruise: The deeper bruise may take some time to come on surface and becomes visible after some time. So, in all custody deaths dead body shall be seen again after dissection is over. Also the dissection procedure drains large amount of blood and hence the pallor caused after such procedure provides a contrast background and bruise becomes visible. In clinical situation a follow up examination may solve the controversy.

Age of bruise : - The red cell disintegrate by haemolysis and haemoglobin is broken downin to 1. Haemosiderin- bluish black to brown 2 Haemotoidin – Green 3. Bilirubin - Yellow. - Colour change starts at periphery and extends inwards to center. Up to few hours- red Few hours to 3 days- blue 4th day- bluish black to brown 5 to 6th day- Green 7 to 12 days- Yellow 2 weeks- normal

Difference between: ANTE MORTEM

and

POST MORTEM BRUISE ( possible up to 2-3 hours)

Vital reaction - present

Absent

Microscopy –- cellular infiltration present

Absent

-- DIFFERENCE BETWEEN Feature 1. CAUSE 2. SITE 3. SURFACE 4. COLOUR

PM LIVIDITY

BRUISE

Capilo venous distension rupture of vessles dependent parts only any where not elevated elevated and swollen blue purple without any change colour changes occurs 5. EFFECT OF Absent on pressure area may be present any where PRESSURE fading- if not fixed no change 6. ON INCISION no extravasation extravasation in sub cutaneous tissue

DIFFERECE BETWEEN Feature 1. Cause 2. Site 3. Shape 4. Margins 5. Inflammation 6. Itching 7. Vesicle 8. Contents 9. Chemical test

ARTIFICIAL BRUISE Marking nut, calatropis Accessible& exposed parts Irregular Well defined, regular present present present Acrid serum Positive for substance

TRUE BRUISE trauma anywhere shape of object ill defined, irregular absent absent absent extravasated blood Negative

MEDICO LEGAL ASPECTS OF BRUISE 1. Except patterned bruise the dimensions and shape of bruise give no idea about type of weapon. 2. Patterned bruise( distance between parallel bruise) correspond to breadth of weapon. 3. Deep tissue bruising of neck is one of the hallmark of neck compression. 4. Genitals may show bruising in sexual offenses 5. They may not become visible till several hours after causation , hence follow up examination is recommended to include or exclude DELAYED BRUISE. 6. Opinion about site of injury shall be guarded in nature as the ECTOPIC BRUISING may also occur at places. 7. Internal contusion and bleeding may be present in cavity without any naked eye evidence of any injury on anterior abdomen.

LACERATED WOUND Definition : It is a tear or split in skin, mucous membrane , muscle or internal organs produced due to stretching beyond elasticity caused by infliction of hard and blunt force Types: 1. Split laceration- Occurs when soft tissue is under the seat of impact gets crushed between two hard objects. - Scalp, chin, bony prominences of limbs. 2.Stretch laceration – The more or less fixed skin is over stretched under or put before bent or broken ends of bone. 3. Tear – combination of over stretching and pulling. - Fall over projected and rough objects and surface. 4. Avulsion- grinding compression by weight and velocity - Wheel of heavy vehicle will forcibly try to drag the skin flap in direction of movement leading to separation of a layer in a flap. 5. Incised looking lacerated wound- Scanty skin and sub cutaneous tissue will produce linear splitting under the seat of impact and produce wound with sharp margins in area like scalp, eye brow, iliac crest.

CHARECTERISTICS : 1. Margins: ragged, irregular and uneven which will extend to whole depth of wound and are also contused. “ Shelving” of margins may be present when force is NOT inflicted perpendicularly. ( One margin over rides another) 2. Subcutaneous and deep tissue: Contused, irregularly torn with tags of soft tissue and muscle fibres , twigs of vessels and nerves . 3. Bleeding : a)Usually do not bleed much as vessels are crushed b) Scalp wounds bleed freely as temporal arteries are bound firmly and unable to contract. c)Lacerations of internal viscera lead to severe internal bleeding with other grave consequences though may have delayed presentation. 4. Hairy area : Hair bulbs show crushing effect in form of irregular separation with reference to breadth and length.

5. Shape: a) linear with Y shaped ends -when shaft of hard and blunt weapon strikes. b) Cresentric -when only part of edge of round head strikes. c) Stellate – when whole surface of round head strilkes. 6. Location: Usually occurs when there is underneath bony prominence COMLICATIONS: 1. Shock – if vital organs are involved. 2. Haemorrhage – Blood loss from major vessel / organ / multiple small vesse. 3. Infection Features of post mortem wound --> Bleeding is absent or negligible --> Vital reaction is absent --> Pale look as there is no contusion of margins

Medico legal importance: 1.Always caused by HARD AND BLUNT OBJECT like, stick, bar, rod, metal pipe, hammer, stone, brick, foot kick etc. 2. Shape may indicate the shape of sticking part of object. 3. Shelving indicates oblique direction . 4. Manner – vehicular accident, assault. CHOP WOUNDS: - Produced by heavy sharp cutting weapons like axe, sword, dhariya, sickle. Difference between Chop laceration Incised looking LW Weapon heavy, sharp hard and blunt hard and blunt Area any where bony prominence scanty skin Margins SHARP IRREGULAR SHARP Hair CUT CRUSHED CRUSHED Bone SHARP CUT -----IREEGULAR FRACTURE------

INCISED WOUND Definition: It is sharp cut wound involving SKIN AND SUB CUTANEOUS TISSUE caused by sharp cutting edge of weapon dragged almost parallel to surface and its LENGTH IS ALWAYS GREATER THAN DEPTH. Method of production : 1.They are produced by Sharp edge of weapon like knife, scalpel, blade, sword, dagger, chopper etc. 2. The sharp edge of weapon either STRIKES or DRAWN over body surface. Characteristics 1. Margins: Always regular, well defined and sharp cut. 2. Dimensions : Length is greatest among all ( than breadth and depth). 3. Direction : :usually Deeper at commencement , depth becomes shallower at termination and ends as a scratch- “ Tailing of wound”.

4. Shape : Usually elliptical in shape with linear scratch at the end. More broad , if underneath muscle fibers are cut transversely. fibers cut transversely:

Fibers cut longitudinally;

5. Hemorrhage: Such wounds bleed freely as vessels are CUT. 6 Beveling effect: Present if weapon is inflicted obliquely; One of the edge as cut obliquely forms a flap which lies on another edge.

Complications: Blood loss, loss of movement if muscle is cut, paralysis if nerve is cut. More chance of infection. Medico legal aspects: 1. Indicates use of sharp cutting weapon. 2. Tailing indicates the direction of wound. 3. Suicidal cut throat and wrist cut are observed.- self inflicted injuries. 4. Defense wound on palmer aspect of hand are seen when victim tries to grasp the sharp cutting weapon as a defense

Age of Incised wound ( In uncomplicated course of injury) Haematoma formation = Fresh up to 12 hours Edge – red, swollen and adherent blood and lymph with leukocyte infiltration= 12 hours Endothelial cell cover surface = over that dry scab = 24 hours. Certain histo- pathological changes – healing process. QUESTION: Can a weapon inflicted once only produce multiple wounds? ANS: Yes, On body surface where there are alternate areas of elevated surface like back of palm, fingers, toes , front of chest due to ribs. STAB WOUND Definition: It is a wound produced when a pointed weapon is forcibly thrust into body in any direction other than parallel to surface and DEPTH IS THE GREATEST DIMENSION AMONG ALL ( than length and breadth) Production : By knife, dagger, sword, arrow, poker , screw driver, broken glass bottle or piece. Possible on any part of body other than head. In head it is possible in TEMPORAL AREA AS IN THIS REGION BONE IS

Length of blade will produce depth of wound Breadth of weapon will produce length of wound

Blade

Thickness of blade will produce breadth of wound

Hilt

Grip / Handle

Characteristics of stab wound: 1.Length: It corresponds to width of lade of weapon. It is always less than the depth. In certain case it may be more than breadth of blade of weapon : 1.As it may be driven more while driven in or out. The part of length with blue line is actual breadth of weapon. The part of length with red line is produced due to cutting action while the weapon is driven in or driven out.

2.

a weapon may not have uniform width through out- the breadth may be less in the tip and it may gradual increase. So, the length of wound produced will depend upon the fact that how much part of blade is driven in.

Length of wound produced

If breadth decreases after increase earlier length will prevail

3. A particular type of weapon which can be opened and such opening will increase its breadth and in turn length of a stab wound . i.e. Closed scissors driven in and opened after some length of it is in body

4. In case of stab wound of Collapsible organs like Lung, intestine the dimensions in collapsed organ are far less than actual as at the time of production of wound organ is in distended condition.

Normal expanded lung

Collapsed lung, due to escape of air as a result of injury, whole lung substance show reduction in dimensions.

5. Improper technique in measuring the dimensions. The shape and dimensions may get altered after death due to loss of elasticity. So, at the time of measurement margins shall be apposed to each other and reconstructed.

Adhesive tap

5. Improper technique in measuring the dimensions. The shape and dimensions may get altered after death due to loss of elasticity. So, at the time of measurement margins shall be apposed to each other and reconstructed.

2. Width:: It corresponds to thickness of blade of weapon. The gaping may be more if underneath muscle fibre run transcersely. 3. Depth: It corresponds to length of blade. It is greatest among all dimensions. The extent of depth will depend up on : 1. How much of blade is introduced- if only some part of blade is introduced than the depth may be less than the actual length of blade. 2. On which body part its is inflicted & whether coupled with compressionOn anterior abdominal wall and chest wall which are compressible which on THRUSTING WITH PRESSURE allows penetration greater than actual length. Such increase in depth will be proportionate to extent of compression.

4. In case of injury to collapsible organs like lung, intestine – the collapse after injury may also reduce the depth measurement. 4. Margins--Regular and sharp cut margins- pointed sharp cutting weapon. --If three are entry and exit wound the margins will be inverted in earlier and everted in later. -- Margins will be irregular – pointed weapon with blunt surface i.e. Screw – driver, poker etc. -- Margins may be everted if weapon is drawn back. 5. Shape: -- Cleavage lines- lines of tension being determined by the direction of the elastic and collage nous fibers in skin. -- If a wound cuts across these lines transversely the gaping will be more and shape will be spindle and if cuts them parallel then shape will be more elliptical

Shape will correspond to cut section of the blade of weapon. -- Single edged weapon – wedge shape- one end sharp and another end is relatively blunt or curved. One end may be curved or straight due to blunt edge of weapon Another end will be pointed due to sharp cutting edge.

-- Double edged weapon will produce spindle or fusiform shape due to two sharp cutting edges.

-- Pointed weapon without sharp edges- Circular wound with irregular margins. i.e. Screw driver, poker. -- Pointed weapon – when twisted in body may alter the shape and breadth accordingly. -- Star shaped or stellate shaped wound1. weapon has two cutting blades in different axis like arrow or sphere. 2. Overlapping of two elliptical wounds.

-- Hilt mark and / or hinge markWhich is superficial and at any of the end of wound

6. Direction: --Indicated by track of wound. --In dead body can be determined by probing, BUT IN LIVING PROBING IS CONTRAINDICATED AS IT MAY RELEASE A BLOOD CLOT ANT INITIATE BLEEDING OR MAY EXTEND THE DEPTH. -- Indicates relative position of victim and direction of infliction. For example, A wound enters the cavity in upwards, backwards and towards right side , is produced by infliction from downwards, forward and left side of wound. -- A single wound with two track in d different direction indicates that weapon has been thrust twice from same external wound. COMPLICATIONS: 1. External and internal haemorrhage. 2. wound infection and its complications 3. Pneumo thorax and pneumoperitoneum in chest and abdominal injuries respectively.

MEDICO LEGAL SIGNIFICANCE: 1. Shape of wound indicates type of weapon. 2. Dimensions- length, breadth and depth indicates dimensions of weapon. 3. Direction indicates position of assailant and victim. 4. Manner can be determined by position, number, direction of wounds- but is quite complex. QUESTION : Can a single weapon produce more than one wound? Answer: Yes . In following cases: 1. Single weapon inflicted for more than once. 2. The weapon may have more than one pointed parts, like open scissors, fork . 3. The wound may be inflicted on body part with narrow breadth like limb. In this case there may be one entry, one exit and one more entry in neighboring part.