Generally, when something hits your head, it is referred to as a coup injury. Conversely, when your head hits something, it is referred to as a contrecoup injury. What do these terms mean? The context here is to understand the acceleration/deceleration biomechanics of brain injury within the meninges of the skull and where in the brain parenchyma is a lesion suspected to be found.
For example, when someone gets hit in the head by a baseball bat, the brain sustains a coup injury at the point of impact. When someone falls and hits their head on the ground, the brain sustains a contrecoup injury at the opposite side of impact. These types of injuries may be associated with cerebral contusions and swelling, concussion, skull fracture, and more serious intra/extracranial hematoma bleeding.
Low-speed coup/contrecoup, high-speed coup/contrecoup, whiplash, and acceleration/deceleration vectors in these types of traumatic events are a more detailed anatomic and clinical narrative for another discussion.
