FM5.1-6,FM14.{1,9-10} | Mechanical Injuries & Wounds — Practice Quiz

Laceration: tearing of skin and deeper tissues by blunt force → irregular, ragged margins with tissue bridges (nerves, blood vessels) traversing the wound base — a pathognomonic feature.

Laceration features: ragged/irregular margins, tissue bridges at base, hair crushed/not cut, surrounding bruising, caused by blunt force. Clean margins without bridges = sharp force (incised/stab).

Incised and stab wounds have clean, sharp margins without tissue bridges (caused by cutting force). Abrasion affects only the epidermis, not full skin thickness.

Stab wound: depth > surface length (penetrating wound made by a pointed weapon). Incised wound: length > depth (slicing action). Both have clean sharp margins.

Wound taxonomy: abrasion (epidermis only), bruise (intact skin), laceration (blunt, ragged + bridges), incised (length > depth, sharp), stab (depth > length, penetrating). Memorise depth-length rule.

Clean margins and subcutaneous involvement occur in both stab and incised wounds. Bruising is more typical of blunt force. Only depth vs. length ratio definitively distinguishes them.

Abrasion = tangential/compression force removing only the epidermis. Dermis intact → healing occurs without scar (unless infected). This superficial nature is the defining feature.

Abrasion: epidermis only; heals without scar; shows direction of force (scratched epithelium piles at the far end). Types: scratch, pressure, grinding (graze), impact abrasion.

Dermis + subcutaneous involvement = laceration or deeper wound. Subcutaneous with intact skin = contusion (bruise). Muscle involvement with skin splitting = deep laceration.

A bruise healing in 5 days is simple hurt — not grievous. Grievous hurt requires permanent/serious consequences (loss of organ, permanent disfigurement, bone fracture, dangerous disease, 20-day incapacitation).

BNS (formerly IPC 320) — 8 categories of grievous hurt: emasculation, permanent blindness (1 or both eyes), permanent deafness, loss of joint use, permanent disfigurement of head/face, bone fracture/dislocation, endangering life, incapacitation > 20 days.

Loss of sight, bone fracture, and permanent disfigurement of face are all specified grievous hurt. A transient bruise is simple hurt under BNS (formerly IPC Section 320).

BNS classifies a wound that endangers life as grievous hurt at the time of injury, regardless of outcome. The forensic classification is determined by the nature of the wound, not the final outcome.

Key forensic principle: grievous hurt is classified by wound nature at the time of examination, NOT by outcome. A life-threatening wound = grievous hurt even if patient survives. Culpable homicide requires actual death.

'Endangering life' is one of the eight grievous hurt categories — applicable even if the patient recovers. Classification is not deferred until death; the wound nature at time of examination determines the opinion.

PMN infiltration begins within 2-4 hours of wounding and is the first histological vital reaction. This is used to estimate wound age and prove antemortem infliction.

Wound age histology timeline: PMN 2-4 hours → epithelial bridging 24-48 h → fibroblasts 3-5 days → collagen 5-7 days → granulation tissue 3-7 days → scar remodelling weeks-months.

Fibroblasts appear at 3-5 days; epithelial bridging begins at 24-48 hours; granulation tissue (neovascularisation) at 3-5 days. PMN infiltration at 2-4 hours is the earliest marker.

The forensic pathologist must NOT speculate on assailant identity or motive — these are for police/court to determine. The medical certificate describes wounds, likely weapon, age, and degree (simple/grievous).

ML wound certificate must NOT include: names of accused, motive, or legal verdict. Must include: wound description, dimensions, diagrams, probable weapon, wound age, simple vs grievous classification.

Wound type, dimension, diagram, weapon opinion, and wound age are all proper forensic medical opinion. Naming an assailant or stating motive exceeds medical scope and can undermine court proceedings.

Chop wounds (from heavy bladed weapons — axe, dao): notched/cleft bone, contused or abraded skin margins (due to weapon weight and impact), may be deep. Incised wounds have clean bone cuts and sharp margins only.

Chop wound vs incised: weapon = heavy vs light blade; bone = notched/cleft vs cleanly cut; skin margins = contused/abraded vs clean; hair = crushed not cut vs cleanly cut.

Clean margins and no abrasion = incised wound (sharp light blade). Depth > length = stab. Chop wounds are heavy-blade (axe) wounds with bone notching and bruised/contused margins.

Refusing to examine an injured person is professional misconduct under MCI/NMC code. In India, Section 357C CrPC (now BNSS equivalent) mandates hospitals to provide first aid in acid attack/sexual assault cases. Refusing can result in disciplinary action.

Medico-legal duty: all registered medical practitioners must examine and issue certificates when requested by police or courts. Refusal = professional misconduct. Emergency treatment always precedes forensic examination.

Police status does not justify refusal. All doctors have a professional and legal duty to examine injured persons, regardless of whether it is a medico-legal case. The examination produces evidence for the court.

Bruise colour progression (haemoglobin breakdown): fresh → Red → Blue/Purple → Green (haemosiderin) → Yellow (bilirubin) → disappears. Approximate: red same day, purple 1-2 days, green 3-5 days, yellow 5-7 days.

Bruise age colour sequence (helpful mnemonic: Ruby Purple Grapes Yield): Red → Purple → Green → Yellow → vanishes. Wide individual variation — report as 'consistent with' rather than exact age.

The sequence follows haemoglobin → methaemoglobin → haemosiderin → bilirubin degradation. Always progresses from fresh red to yellow before disappearing.

Treatment always takes precedence over forensic examination. The doctor's primary duty is the patient's wellbeing. Forensic collection proceeds after or concurrent with treatment, not before.

ML examination order: (1) treat life-threatening injuries (ABCDE), (2) conduct forensic examination once stable, (3) collect evidence, (4) document and issue certificate. Treatment first — always.

Forensic evidence collection must not delay emergency treatment. Police requisition is a legal requirement but emergency care cannot be withheld pending paperwork.

Defence wounds occur when a person raises their arms to protect themselves from attack: ulnar border of forearm and dorsum of hands are most commonly injured by the incoming weapon.

Defence wounds: forearm (ulnar border), dorsum of hand, palm, fingers. Indicate the victim was conscious and able to respond. Their presence argues against incapacitation at time of attack.

Back of scalp = fall or blunt impact. Anterior chest = direct assault. Defence wounds specifically occur on the protecting limb — forearm ulnar border and dorsal hand during arm-raising defence.