A skull fracture is when a trauma to the head causes a break in one or more of the bones surrounding the brain or to other structures within the skull. While a skull facture, on its own, is not a very serious injury, it may be coupled with a more serious injury to the brain. For example, bone fragments may damage the delicate tissues of the brain or blood vessels. If a fracture causes damage to a major blood vessel, considerable bleeding may ensue, frequently resulting in hematomas. Additionally, a skull fracture can cut apart a cerebral artery, dangerously decreasing blood flow to the brain. Skull fractures in which the bone protrudes from the skin are referred to as compound fractures.

Skull fractures can be divided roughly into three types: linear, depressed, and basilar. Linear skull fractures are not uncommon, occurring in nearly 70 percent of severe head injuries. A linear skull fracture refers to a relatively simple and straight break in the skull bone. They are most common in children and can be caused by minor traumas to the head; for example, being struck by a blunt object, falling on a hard surface, or motor vehicle accidents. Unless there is injury to the brain, a linear skull fracture is not a serious injury. However, in rare instances, due to brain swelling, a linear fracture can grow; this can result in more dangerous complications.

A diastatic fracture is a type of linear fracture occurring in young children. It is a separating of the skull bones, before they have entirely fused, caused by an impact with a broad surface, such as a wall. Depressed skull fractures are less common but more serious, occurring in slightly more than 10 percent of head injuries. Depressed skull fractures are usually the result of a trauma caused by heavy but small objects, i.e. rocks, hammers, etc. The injury itself is a dent or depression in the skull, which, in some circumstances, may put pressure on the brain. If the depth of the depression is equal to or greater than the thickness of the skull, surgery is usually necessary in order to raise the bones and make certain that the brain was not injured. Smaller depressions typically do not require surgery unless further injuries are found. When a depressed skull fracture is comminuted, the skull bone is broken into a number of pieces, greatly increasing the risk that brain will be lacerated by the sharp bits of bone.

Basilar skull fractures are quite rare, occurring in about 4 percent of severe head injuries. A basilar skull fracture is when a considerable force breaks the bones forming the base of the skull. Because basilar skull fractures frequently connect to the sinus cavities (allowing are into the skull), there is a greater risk of infection. Surgery, however, is usually not necessary, unless other conditions necessitate it. The signs of basilar skull fractures are quite dramatic, including blood in the sinuses, a clear fluid coming from the nose and/or ears, blood collecting beneath the skin around the eyes (raccoon eyes), and Battle’s sign (bruising behind ears, caused by blood collecting).