A sharp object cuts and divides the tissues as it penetrates, but a wound produced by blunt impact tears, shears, and crushes. Falls, collisions, or blows with a blunt instrument such as a hammer, brick, bat, fist, or pipe typically result in blunt force injury. Excessive bleeding into the adjacent soft tissues usually occurs. Hemorrhage of similar magnitude is practically never seen in the margins of cuts and stab wounds. The manifestations of blunt trauma differ depending on the force and the nature of the impact. The three recognized lesions are contusion, abrasion, and laceration. A contusion or bruise signifies hemorrhage into the impact. The three recognized lesions are contusion, abrasion, and laceration. A contusion or bruise signifies hemorrhage into the skin, the tissues under the skin, or both. It is usually the result of a blow or squeeze that crushes the soft tissues and ruptures blood vessels but does not break the skin. Examples include a black eye cause by a fistfight, scalp hemorrhage from a fall, and black and blue marks appearing after an arm has been squeezed tightly. Some bruises are patterned, and their recognition may help to reconstruct the circumstances of injury. The imprint of a steering column on the chest of an automobile driver is an example. An abrasion is due to scraping of the skin with removal of its superficial layers. It is frequently difficult to distinguish between an abrasion sustained during life from one sustained after death because bleeding does not usually occur due to the superficial nature of abrasion. Abrasions, like contusions, are often characteristically patterned. A laceration is a tear produced by blunt trauma. The force and direction determine appearance, depth, and associated injuries such as fractures. Injuries caused by hammer blows and bottles are examples of lacerations. Examination of skeletal injuries, particularly skull fractures, often reveals the type of violence involved. Extensive photographs and 10 references are included. For related documents, see NCJ 69731-32 and 69734-47.