When a knock to the head does not fracture the skull but nevertheless causes temporary brain damage as a result of the way the brain has been shaken about, this is called concussion. Bleeding into the space occupied by the brain, from a knock to the head, or a skull fracture or penetrating injury, is called a compression injury. Bleeding inside the skull puts pressure on the brain and may have serious consequences. In all cases of head injury, and particularly with any penetrating head injury, the level of consciousness will probably be impaired. You should treat the casualty according to the general principles outlined above, arranging rapid transfer to hospital. A head injury that results in bleeding from the scalp may look more serious than it is because this area of skin is well supplied with blood and tends to bleed profusely. However, you should bear in mind that a skull fracture may also have been inflicted; and it would therefore be wise for the casualty to seek medical advice even if consciousness is not impaired. If someone develops a headache or becomes drowsy some time after a blow to the head – even days later -he or she should see a doctor, because slow bleeding may be occurring inside the skull.