Interpretation of Injury Patterns
Pattern recognition is the heart of forensic injury interpretation. You must connect mechanism to morphology: blunt force (contusions, abrasions, lacerations with tissue bridges, fractures), sharp force (incised wounds, stab wounds with clean margins and depth greater than length), gunshot wounds (entry with abrasion collar, soot and tattooing at close range, exit wounds, track and re-entry), and asphyxia (petechiae, ligature marks, hyoid and thyroid fracture patterns).
Concept traps are frequent. Abrasion direction indicates the direction of force, not the direction of travel of the body. A laceration is distinguished from an incised wound by tissue bridging and irregular margins. In gunshot wounds, soot and stippling mean close range, not contact; a muzzle imprint and searing indicate contact. Stab wound depth can exceed apparent length because tissue stretches. Defense wounds sit on the forearms and hands; hesitation marks are parallel and shallow on the wrists. Postmortem animal predation mimics sharp injury but lacks hemorrhage.
Worked example
A body shows a linear abrasion with a clean tail of scraped epidermis pointing toward the feet on a road. Rule of thumb: the abrasion tail points in the direction the force moved across the skin, so the injury was produced by force directed toward the feet. If the tail points away from a suspect's claimed direction of impact, the history is inconsistent.
Always correlate pattern, hemorrhage (antemortem versus postmortem), and scene reconstruction before assigning mechanism.