FM6.1-2,FM7.1-2,FM14.11 | Firearm, Blast & Regional Injuries — Glossary

Not to be confused with the firearm abrasion collar; refers to the zone of dried, abraded skin margin seen in some scalp lacerations from blunt objects with a rough surface.

A narrow ring of dried, brownish abrasion around an entrance wound; caused by the bullet's rotating surface stretching and scraping the epidermis as it enters; absent at exit wounds.

Necrosis of renal tubular epithelial cells; in crush syndrome, caused by myoglobin precipitation in tubules; leads to oliguric renal failure requiring dialysis.

Indian legislation governing manufacture, sale, possession, and use of firearms; obliteration of serial number and possession without licence are offences under this Act.

Soot deposited on the skin surface around the wound from propellant combustion; requires very close proximity to the muzzle (<15 cm); can be wiped away, distinguishing it from tattooing.

Primary blast injury to the lungs — alveolar haemorrhage, disrupted alveolar walls, and possible air embolism — caused by the overpressure wave; no external chest wall injuries.

A transverse fracture of the tibia and/or fibula at the height corresponding to the vehicle's bumper contact point on the victim's leg; measured from the heel to determine bumper height and thereby identify the vehicle class.

Compression fracture of the calcaneum (heel bone) from axial loading in a feet-first fall from height; bilateral calcaneal fractures are the hallmark of suicidal or accidental falls from height.

The internal diameter of a firearm barrel, expressed in inches or millimetres; also the designation for the cartridge type the weapon fires (e.g., .38 caliber, 9 mm caliber).

The complete unit of ammunition comprising case, primer, propellant charge, and projectile (bullet).

A documented, unbroken record of every person who handled a forensic exhibit from scene to court; any gap makes the exhibit legally challengeable.

A constriction at the muzzle end of a shotgun barrel that controls pellet spread after firing; tighter choke produces a narrower pattern at a given range.

Brain injury at the pole opposite the impact site; occurs when a moving head decelerates suddenly, causing the brain to impact the far skull wall by inertia; most severe in falls landing on the occiput (frontal pole injury).

Brain or skull injury at the site of direct impact; occurs when a moving object strikes a relatively stationary head.

Systemic rhabdomyolysis following prolonged muscle compression; characterised by myoglobinuria (tea-coloured urine), hyperkalemia (lethal on release), and acute tubular necrosis leading to renal failure.

Skull fracture with inward displacement of a bone segment below the outer table level; caused by high-velocity impact over a small area; the fragment depression pattern may match the weapon shape.

Widespread axon shearing throughout the white matter from rotational acceleration-deceleration forces; presents with coma disproportionate to CT findings; confirmed by beta-APP immunostaining at post-mortem.

Extensive linear abrasions along the body surface caused by the victim being dragged under or behind a vehicle; distribution and direction indicate the victim's position and direction of drag.

Haematoma between the inner skull table and the outer dura, typically from middle meningeal artery rupture at a temporal skull fracture; CT shows biconvex lens-shaped collection; classic lucid interval before deterioration.

A bullet type with a soft lead core encased in a harder metal jacket; designed to maintain shape on impact and produce a smaller wound cavity compared to expanding bullets.

Microscopic particles produced by firearm discharge — primarily from the primer, propellant, and bullet — that deposit on the wound margins, shooter's hands, and nearby surfaces; detected by SEM-EDX analysis.

Haemorrhage within the spinal cord substance from trauma or vascular injury; extent of haemorrhage determines degree of permanent neurological deficit.

Transverse fracture of the skull base from side-to-side head compression (e.g., vehicle wheel over head); separates the skull into anterior and posterior portions; usually fatal.

A bullet type with a cavity in the nose that causes the bullet to expand (mushroom) on impact, increasing its cross-sectional diameter and producing a larger wound cavity.

Elevated serum potassium; in crush syndrome, caused by massive release of intracellular K+ from damaged muscle cells; causes peaked T-waves, wide QRS, and ventricular fibrillation at high levels.

Indian Penal Code provision for causing death by a rash or negligent act not amounting to culpable homicide; the standard charge in road traffic fatalities; maximum punishment 2 years imprisonment or fine or both.

Indian Penal Code provision defining eight categories of grievous hurt; forensic physicians must determine which category applies to documented injuries to guide criminal charges.

A period of apparent recovery or consciousness between the initial head injury and secondary deterioration from expanding intracranial haemorrhage; classic (but not universal) in epidural haematoma from middle meningeal artery bleeding.

The speed of the bullet as it exits the barrel, measured in metres per second; the primary determinant of tissue destruction through kinetic energy (KE = ½mv²).

The presence of myoglobin in the urine, giving it a characteristic dark brown/tea colour; indicates significant muscle destruction; myoglobin precipitates in renal tubules causing ATN.

Rupture of a solid viscus (liver, spleen, stomach, bladder) from sudden compressive force exceeding tissue failure threshold; seen in run-over injuries and severe abdominal blunt trauma.

The tissue actually destroyed along the bullet track — crushed, lacerated, and non-viable; determined primarily by bullet diameter and degree of deformation.

A smooth concave skull depression without fracture lines; seen in infants/young children whose elastic skulls deform without cracking; in adults indicates severe force.

Injury caused directly by the overpressure wave from an explosion; affects air-tissue interfaces — blast lung (alveolar haemorrhage), tympanic membrane rupture, bowel perforation; no external marks.

The initial contact between the vehicle and the victim — typically the bumper striking the lower limbs in a pedestrian collision; produces the bumper fracture.

A percussion-sensitive chemical compound at the base of the cartridge case; struck by the firing pin, it ignites and initiates combustion of the propellant.

The chemical charge (black powder or smokeless powder) in a cartridge that burns rapidly on ignition to produce expanding gas, propelling the bullet down the barrel.

All other blast-related injuries: burns, crush injuries from building collapse, toxic gas inhalation (CO, cyanide).

Neurological injury of the spinal cord or nerve roots from jolting/jarring forces in a railway accident, without necessarily producing a vertebral fracture; presents as a spectrum from transient paresis to permanent paraplegia.

The distance between the muzzle of the weapon and the target at the moment of discharge; estimated from entrance wound features per Reddy's range classification.

A handgun with a rotating multi-chamber cylinder; spent cartridge cases are retained in the cylinder after firing, unlike semi-automatic pistols where cases are ejected.

Destruction of skeletal muscle cells releasing intracellular contents (myoglobin, CK, potassium) into the circulation; the primary event in crush syndrome.

Helical grooves cut into the inner surface of a rifle or pistol barrel; imparts spin to the bullet for accuracy and leaves characteristic striations on the bullet for ballistic matching.

Penetrating fragmentation wounds from bomb casing, projectiles, or structural debris propelled by the explosion; most common cause of death in explosive attacks.

The victim being thrown from the vehicle after the primary impact and landing on the ground or another surface; often produces the most severe head injuries.

Scanning electron microscopy with energy-dispersive X-ray spectroscopy; the accepted standard for GSR analysis, identifying individual particles by morphology and elemental composition (Pb+Ba+Sb in traditional primers).

A barrel without rifling grooves, used in shotguns; fires multiple pellets or a single slug without spin stabilisation.

Transient functional disruption of the spinal cord without structural damage; complete recovery within hours; forensically important as it explains immediate paralysis that resolves fully.

Haematoma between the dura and arachnoid, from bridging vein rupture in deceleration injury; CT shows crescent-shaped collection; classified as acute, subacute, or chronic.

An exit wound where the skin is pressed against a firm surface at the moment of exit; the result is a smaller, abraded wound that may closely mimic an entrance wound.

Mechanical embedding of unburned or partially burned powder particles in the skin surrounding the wound; ranges 15–60 cm (intermediate range); cannot be wiped away, distinguishing it from blackening.

The transient radial displacement of tissue caused by the bullet's pressure wave; significant only at high velocity (>750 m/s); causes secondary disruption of inelastic organs.

Blunt force injuries caused by the victim's body being thrown against a solid object by the blast wind.

Thin strands of dermis/connective tissue crossing the gap of a wound; present in lacerations (blunt force), absent in incised wounds (sharp force); the key distinguishing feature.

The path of a bullet from the muzzle to the target; determined at autopsy by the wound track direction to reconstruct the shooter's position.

A patterned injury on the skin imprinted by the tyre tread as the wheel passes over the body; orientation indicates direction of vehicle travel; tread pattern can be matched to the tyre type.

A teaching construct for pedestrian-vehicle collision injuries: lower limb fracture (bumper level) + trunk/pelvic injury (bonnet level) + head injury (ground level); all three zones need not be present for the pattern to indicate pedestrian impact.

The science of bullet behaviour in tissue — energy transfer, temporary and permanent cavity formation, fragmentation, and yaw — that explains wound characteristics.

The sideways rotation of a bullet off its long axis during flight or travel through tissue; increases the bullet's effective cross-section and energy deposition in tissue.