Forensic Medicine & Toxicology
High-yield MBBS Forensic Medicine & Toxicology question bank — medical jurisprudence, identification, thanatology, injuries, asphyxia, forensic sexology and toxicology, at Reddy’s / Parikh depth.
12chapters144questions77High-Yield
Definition
An injury (wound) is any harm caused to body, mind, reputation or property; an abrasion is destruction of the superficial layers of skin by friction.
Classification of Mechanical Injuries
- Blunt force — abrasion, contusion, laceration
- Sharp force — incised wound, stab wound, chop wound
- Firearm — entry and exit wounds
- Thermal, chemical, electrical and radiation injuries
- Legally: simple, grievous and dangerous
Abrasions
- Scratch (linear) — by pin, nail, thorn; indicates direction
- Graze (sliding/brush burn) — tangential force; tags of epidermis heap up at the terminal end, giving direction
- Pressure (crushing) abrasion — ligature mark, teeth bite
- Impact (imprint) abrasion — reproduces the pattern of the object (tyre tread, radiator grill)
- Healing: red → reddish-brown scab 12–24 h → scab dries 2–3 days → falls off 5–7 days, leaving no scar
Because only epidermis is lost, abrasions heal without scarring. Type Example Scratch Nail mark Graze Road surface Pressure Ligature mark Imprint Tyre tread Applied
- Abrasions indicate the site of impact and direction of force
- Patterned abrasions may identify the weapon or vehicle
🔑KEY POINTS TO REMEMBER- Injuries: blunt force, sharp force, firearm, thermal, chemical, electrical.
- Abrasion types: scratch, graze, pressure and imprint.
- Heal in 5–7 days without scarring; indicate direction and object.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
A contusion (bruise) is extravasation of blood into the tissues from rupture of small vessels caused by blunt force, with the overlying skin intact.
Features & Colour Changes
- Skin remains intact; swelling, pain and discoloration
- Red → blue (few hours) → bluish-black (1–3 days) → greenish (4–5 days) → yellow (7–10 days) → normal (14–15 days)
- Colour change is due to breakdown of haemoglobin — haemosiderin, biliverdin, bilirubin
- Changes appear from the periphery towards the centre
- Patterned bruise — railway-track (tramline) bruising from a rod or stick, indicating the weapon
Modifying Factors & Medicolegal Importance
- More marked in children, the elderly, women, obese and lax tissues (eyelid, scrotum)
- Less in tense tissue such as palms and soles
- Aggravated by bleeding disorders, scurvy, anticoagulants
- Ectopic (migratory) bruise — appears at a site distant from impact (black eye from forehead injury)
- Age of injury, nature of weapon and manner of assault can be inferred
- Distinguish from postmortem lividity
Haemoglobin breakdown produces the predictable colour sequence. Colour Age Red/blue 0–3 days Green 4–5 days Yellow 7–10 days Applied
- On incision a bruise shows extravasated blood in tissue; lividity does not
- Colour dating is only approximate — avoid stating precise ages
🔑KEY POINTS TO REMEMBER- Contusion is extravasated blood with intact overlying skin.
- Colour sequence: red-blue, bluish-black, green (4–5 d), yellow (7–10 d).
- Patterned (tramline) bruising indicates the weapon; ectopic bruises migrate.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
A laceration is a tear of tissue by blunt force, whereas an incised wound is a clean cut produced by a sharp-edged weapon.
Laceration
- Caused by blunt force — stick, stone, fall, machinery
- Irregular, ragged margins with abrasion and bruising
- Tissue bridges of nerves and vessels across the depth — characteristic
- Hair bulbs crushed; bleeding relatively less
- Types: split, stretch, avulsion, tear, cut (grinding)
- Contaminated — more prone to infection; heals with scarring
Incised Wound
- Caused by sharp-edged weapon — knife, blade, glass
- Length greater than depth and width
- Clean-cut, everted margins; no abrasion or bruising; no tissue bridges
- Hair cleanly cut; bleeding profuse
- Spindle-shaped due to skin retraction; tailing indicates direction
- Suicidal cuts show hesitation marks on accessible sites (neck, wrist)
Presence of tissue bridges is the single best distinguishing feature. Feature Laceration Incised Margins Ragged Clean-cut Tissue bridges Present Absent Bleeding Less Profuse Hair Crushed Cut cleanly Applied
- A laceration over a bony prominence may mimic an incised wound — look for tissue bridges
- Direction of incised wound: deeper at the beginning, tailing at the end
🔑KEY POINTS TO REMEMBER- Laceration is a blunt-force tear with ragged margins and tissue bridges.
- Incised wound is a clean sharp cut, longer than deep, bleeding profusely.
- Tissue bridges distinguish the two even over bony prominences.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
A stab (punctured) wound is produced by a pointed weapon driven into the body, with the depth greater than its length and width.
Features
- Caused by knife, dagger, screwdriver, needle, spear, arrow
- Depth exceeds the surface dimensions — the defining feature
- Margins clean-cut if the weapon is sharp; abraded and bruised if blunt
- Shape reflects the weapon: single-edged → wedge-shaped (one sharp, one blunt angle); double-edged → spindle/elliptical with both angles sharp
- Wound may be longer than the blade width due to movement, or deeper than the blade length if tissues are compressed
Medicolegal Importance
- Usually homicidal; occasionally suicidal (chest, over the heart) or accidental
- Little external bleeding but severe internal haemorrhage — death from haemorrhage, air embolism, pneumothorax or infection
- Direction and depth indicate the relative position of assailant and victim
- Number of wounds suggests a struggle; defence wounds on hands and forearms suggest homicide
- Track should be traced by layer dissection, never by probing
The small external wound conceals major internal damage. Weapon Wound shape Single-edged Wedge-shaped Double-edged Spindle/elliptical Round (needle) Slit-like Applied
- Never probe the track — it creates artefacts and false tracks
- Opinion on the weapon should state ‘consistent with’, not ‘caused by’
🔑KEY POINTS TO REMEMBER- Stab wound: depth greater than length and width.
- Single-edged weapons give wedge-shaped, double-edged give spindle-shaped wounds.
- Usually homicidal; small external wound with major internal haemorrhage.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Under the Indian Penal Code, injuries are classified as simple hurt or grievous hurt, determining the punishment for the offence.
Definitions
- Hurt (Section 319 IPC) — bodily pain, disease or infirmity caused to any person
- Simple hurt — any hurt not amounting to grievous; heals rapidly without permanent damage
- Grievous hurt (Section 320 IPC) — eight specified categories
- Dangerous injury — endangers life; not a separate legal category but noted in the certificate
The Eight Kinds of Grievous Hurt (Section 320)
- Emasculation
- Permanent privation of the sight of either eye
- Permanent privation of the hearing of either ear
- Privation of any member or joint
- Destruction or permanent impairment of the powers of any member or joint
- Permanent disfiguration of the head or face
- Fracture or dislocation of a bone or tooth
- Any hurt that endangers life, or causes the sufferer to be in severe bodily pain, or unable to follow ordinary pursuits, for 20 days
The eight statutory categories are the sole test of grievous hurt. Type Section Punishment Simple hurt 319/323 Up to 1 year Grievous hurt 320/325 Up to 7 years Applied
- Doctor states the nature of injury; the court decides the offence
- Defer the final opinion until X-rays and follow-up are complete
🔑KEY POINTS TO REMEMBER- Hurt defined in Section 319; grievous hurt in Section 320 IPC.
- Eight categories include emasculation, loss of sight/hearing, fracture, 20-day disability.
- The doctor describes the injury; the legal classification rests with the court.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Defence wounds are injuries sustained while a victim attempts to protect themselves from an attack, and are strong evidence of homicide.
Sites & Types
- Active defence — grasping the weapon: cuts on the palm and fingers, especially the web spaces
- Passive defence — warding off the blow: injuries on the ulnar (outer) border of the forearm, backs of hands
- Also on the outer aspect of arms, shoulders, thighs and legs when curled up
- Sharp weapons → incised and stab wounds; blunt weapons → bruises, abrasions and fractures of ulna (parry fracture)
Medicolegal Importance
- Strongly indicate homicide and that the victim was conscious and able to resist
- Absence suggests the victim was asleep, unconscious, intoxicated, restrained, taken by surprise, or that death was suicidal
- Indicate a struggle, hence trace evidence may be present under the nails
- Their presence effectively excludes suicide
- Must be distinguished from hesitation cuts of suicide, which are on accessible sites and parallel
The site of the wound reveals how the victim tried to protect themselves. Type Site Active Palms, fingers Passive Ulnar forearm Blunt Parry fracture of ulna Applied
- Collect nail clippings and scrapings for the assailant’s DNA
- Photograph both hands and forearms carefully
🔑KEY POINTS TO REMEMBER- Defence wounds occur on palms, fingers and the ulnar border of forearms.
- They strongly indicate homicide and a conscious, resisting victim.
- Absence suggests the victim was asleep, unconscious or that death was suicidal.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Distinguishing antemortem from postmortem wounds depends on the presence of vital reaction — the body’s response to injury during life.
Antemortem Wound
- Profuse bleeding, arterial spurting; blood clotted and infiltrated into tissue planes
- Margins gape and are everted (retraction of living tissue)
- Signs of inflammation — redness, swelling, leucocyte infiltration, later granulation tissue
- Enzyme reaction positive (histamine, serotonin raised at wound margin)
- Evidence of healing if survival was prolonged
Postmortem Wound
- Little or no bleeding; blood does not clot firmly and can be washed away
- Margins do not gape; edges are close and not everted
- No inflammatory or vital reaction; no leucocyte infiltration
- No healing
- Difficulty: wounds inflicted just before or immediately after death may show equivocal findings
- Histology and biochemical tests help resolve doubtful cases
Vital reaction is the decisive criterion in every case. Feature Antemortem Postmortem Bleeding Profuse Minimal Clot Infiltrated Washable Margins Gaping, everted Closed Inflammation Present Absent Applied
- Postmortem wounds may be inflicted to simulate an assault or conceal a crime
- Histopathology of the wound margin is the most reliable confirmation
🔑KEY POINTS TO REMEMBER- Antemortem wounds show vital reaction: bleeding, infiltrated clot, gaping, inflammation.
- Postmortem wounds bleed little and show no inflammatory response.
- Wounds around the time of death may be equivocal — use histology.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Self-inflicted wounds are produced by a person on their own body; fabricated (fictitious) wounds are inflicted to support a false accusation.
Characteristic Features
- Situated on accessible parts — front and left side of the body in a right-handed person
- Vital areas spared — eyes, nipples, genitals
- Multiple, parallel, superficial wounds of similar depth
- Clothing usually undamaged or damage does not correspond to the wounds
- No defence wounds; no sign of a struggle at the scene
- Weapon usually available and often still present
Motives & Medicolegal Importance
- To bring a false charge against an enemy
- To claim compensation or insurance; to avoid duty, military service or punishment
- To simulate robbery or attack; to gain sympathy
- Also in mental illness and malingering
- Bringing a false charge is an offence — the doctor’s opinion is decisive
- Correlate wounds, clothing, scene and history before opining
Discrepancy between wounds and clothing is often the giveaway. Feature Self-inflicted Homicidal Site Accessible Anywhere Depth Uniform, shallow Variable, deep Clothing Undamaged Cut/torn Applied
- Always examine the clothing alongside the wounds
- Give the opinion cautiously and in writing
🔑KEY POINTS TO REMEMBER- Self-inflicted wounds are on accessible sites, parallel, superficial, sparing vital areas.
- Clothing is usually undamaged and defence wounds are absent.
- Fabricated wounds are made to support a false charge — itself an offence.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Hesitation (tentative or trial) cuts are multiple superficial incised wounds made by a person before delivering the final fatal cut, and strongly indicate suicide.
Features
- Multiple, parallel, superficial incisions
- Situated close to and alongside the fatal wound
- Common sites: front and sides of the neck, front of the wrist, front of elbow, groin
- Result from indecision and fear before the final determined cut
- The final wound is deeper and more decisive
- Sites are always accessible to the person’s own hand
Medicolegal Importance
- Almost diagnostic of suicide
- Accompanied by other suicidal features — weapon at the scene, cadaveric spasm gripping the weapon, no defence wounds, clothing lifted away from the site
- Suicidal throat cuts run obliquely from left to right, high on the left, in right-handed persons
- Distinguish from homicidal cut throat — deep, single, horizontal, with defence wounds
- Absence does not exclude suicide
The shallow trials beside a deep final wound are the signature of suicide. Feature Suicidal Homicidal Hesitation cuts Present Absent Defence wounds Absent Present Site Accessible Any Applied
- Look for the weapon and old healed scars of previous attempts
- Photograph the whole area to show the pattern of cuts
🔑KEY POINTS TO REMEMBER- Hesitation cuts are multiple parallel superficial incisions beside the fatal wound.
- Found on neck, wrist and other accessible sites — almost diagnostic of suicide.
- Contrast with homicidal wounds, which have defence injuries and no trial cuts.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
A chop wound is produced by a heavy weapon with a cutting edge, combining the features of an incised wound and a laceration.
Features
- Caused by axe, hatchet, sword, chopper, meat cleaver, spade, machete
- Wound is deep, gaping, and larger than the weapon’s edge
- Margins clean-cut but contused and abraded
- Underlying bone is commonly cut, notched or fractured — characteristic
- May show a bevelled or wedge-shaped defect in bone indicating the direction of the blow
- Often associated with severe internal damage and profuse bleeding
Medicolegal Importance
- Almost always homicidal; occasionally accidental (machinery, agricultural implements); rarely suicidal
- Common sites: head, neck and shoulders
- The bone defect may reproduce the weapon’s edge — allowing weapon identification
- Multiple chop wounds indicate a determined attack
- Death from haemorrhage, brain injury or cervical spine injury
- Defence wounds on hands and forearms are common
The weight of the weapon adds crushing to the cutting effect. Feature Detail Weapon Axe, sword, chopper Bone Cut or notched Manner Usually homicidal Applied
- Preserve the bone for comparison with the suspected weapon
- Radiograph the region to document bone injury
🔑KEY POINTS TO REMEMBER- Chop wounds combine incised and lacerated features, made by heavy edged weapons.
- Underlying bone is typically cut or notched, preserving the weapon pattern.
- Usually homicidal, involving head, neck and shoulders.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Estimating the age of an injury from its stage of healing is important in determining when an assault occurred.
Abrasion and Contusion
- Abrasion — fresh red; scab 12–24 h; reddish-brown 2–3 days; brownish-black 4–7 days; scab falls off 5–7 days
- Contusion — red → blue (few hours) → bluish-black (1–3 days) → green (4–5 days) → yellow (7–10 days) → normal (14–15 days)
- Colour changes are approximate and vary with site, depth and individual
Incised Wounds and Fractures
- Incised wound: 12 h — margins swollen, adherent blood; 24 h — continuous layer of leucocytes; 36–72 h — epithelium proliferates; 3–5 days — capillaries and fibroblasts; 1–2 weeks — scar tissue forms
- Fracture: haematoma (hours), granulation tissue (days), callus visible on X-ray at 2–3 weeks, consolidation 6–12 weeks
- Histology of the wound margin is the most reliable method
- Modified by infection, nutrition, age, diabetes, steroids and blood supply
The stage of repair, not appearance alone, dates the injury. Injury Timing marker Abrasion scab 12–24 h Bruise green 4–5 days Fracture callus 2–3 weeks Applied
- Always express age as a range, never an exact time
- Correlate with the alleged time of assault in the certificate
🔑KEY POINTS TO REMEMBER- Abrasion scabs at 12–24 h and falls off in 5–7 days.
- Bruise turns green at 4–5 days and yellow at 7–10 days.
- Fracture callus is visible on X-ray at 2–3 weeks; give a range, not a fixed age.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.Definition
Death from wounds may occur immediately, early or late, from mechanisms directly or indirectly related to the injury.
Immediate and Early Causes
- Haemorrhage — commonest cause; loss of about one-third of blood volume is dangerous
- Injury to a vital organ — brain, heart, spinal cord, brainstem
- Shock — primary (neurogenic, vagal inhibition) or secondary
- Air embolism — wounds of neck veins; fat embolism — long-bone fractures
- Mechanical asphyxia — aspiration of blood, pneumothorax, laryngeal injury
Delayed Causes
- Infection — septicaemia, peritonitis, meningitis, tetanus, gas gangrene
- Pulmonary embolism from deep vein thrombosis after immobilisation
- Acute kidney injury — crush syndrome, hypovolaemia
- Surgical and anaesthetic complications; ARDS, multiorgan failure
- Starvation and neglect in helpless persons
- The chain of causation must be shown to link injury to death
Even a delayed death may be legally attributed to the original injury. Timing Cause Immediate Haemorrhage, organ injury Days Infection, embolism Weeks Organ failure Applied
- Delayed death does not absolve the assailant if causation is unbroken
- Document the full sequence from injury to death in the report
🔑KEY POINTS TO REMEMBER- Haemorrhage is the commonest immediate cause of death from wounds.
- Other immediate causes: vital organ injury, shock, air and fat embolism.
- Delayed causes include infection, tetanus, pulmonary embolism and organ failure.
📚SOURCES: The Essentials of Forensic Medicine and Toxicology (K.S. Narayan Reddy); Textbook of Forensic Medicine and Toxicology (V.V. Pillay); Modi’s Textbook of Medical Jurisprudence and Toxicology.