Skull fracture:

Although the skull is tough, resilient, and provides excellent protection for the brain, a severe impact or blow can result in fracture of the skull and may be accompanied by injury to the brain. Some of the different types of skull fracture include:

• Simple: a break in the bone without damage to the skin
• Linear or hairline: a break in a cranial bone resembling a thin line, without splintering, depression, or distortion of bone
• Depressed: a break in a cranial bone (or "crushed" portion of skull) with depression of the bone in toward the brain
• Compound: a break in or loss of skin and splintering of the bone. Along with the fracture, brain injury, such as subdural hematoma (bleeding) may occur.