Penetrating head injury

A penetrating head injury, or open head injury, is a head injury in which, at minimum the dura mater — the outer layer of the meninges — is breached. Penetrating injuries can be caused by high-velocity projectiles or objects of lower velocity such as knives, or bone fragments from a skull fracture that are driven into the brain. Head injuries caused by penetrating trauma are serious medical emergencies and frequently cause irreversable brain damage, permanent disability, or death.

A penetrating head injury involves "a wound in which an object breaches the cranium but does not exit it." In contrast, a perforating head injury is a wound in which the object passes through the head and leaves an exit wound. The causative object does not itself need to necessarily progress through the exit wound it causes. Tangential head injuries refer to incidents where an object induces trauma to the head in such a way that, while it may bounce off the skull, the impact nevertheless is forceful enough to push pieces of the skull into the brain.