Skull

Bony structure in the head that supports the structures of the face and forms a protective cavity for the brain.

The skull is composed of two parts: the cranial bone and the mandible. The skull forms the anterior most portion of the skeleton and is a product of encephalization, housing the brain, many sensory structures (eyes, ears, nasal cavity), and the feeding system.

Functions of the skull include protection of the brain, fixing the distance between the eyes to allow stereoscopic vision, and fixing the position of the ears to help the brain use auditory cues to judge direction and distance of sounds. In some animals, the skull also has a defensive function (e.g. horned ungulates); the frontal bone is where horns are mounted. The English word “skull” is probably derived from Old Norse “skalli” meaning bald, while the Latin word cranium comes from the Greek root κρανίον (kranion).

The skull is made of a number of fused flat bones.

see frontal bone

temporal bone

parietal bone

occipital bone…

As pressure within the skull increases, brain tissue displacement can lead to brain herniation, resulting in disability or death.

The skull is a rigid, non-expandable compartment, therefore increased intracranial volume may lead to uncontrolled intracranial hypertension with subsequent cerebral ischemia and tissue death. The most common cause of this condition is traumatic brain injury (TBI) and stroke. However, it can also occur in the context of hydrocephalus, tumors, infections, hemorrhage, and certain encephalopathies. At the beginning of the 20th century, neurosurgeons such as Kocher and Cushing systematically described techniques for removing cranial bone flaps to treat pathologies that caused an increase in intracranial pressure ¹⁾

see Skull tumor.