what is a skull

The skull is the bony structure that encases and protects the brain. It is composed of 22 bones in most adult specimens, which come together via cranial sutures. The skull is subdivided into two regions: the neurocranium, which protects the brain, and the viscerocranium, which forms the face. The neurocranium is the part of the skull that directly houses the brain, while the viscerocranium includes the rest of the bones of the skull. The skull is composed of four types of bone: cranial bones, facial bones, ear ossicles, and hyoid bone. However, two parts are more prominent: the cranium and the mandible. In humans, these two parts are the neurocranium (braincase) and the viscerocranium (facial skeleton) that includes the mandible as its largest bone. The skull forms the anterior-most portion of the skeleton and is a product of cephalisation—housing the brain, and several sensory structures such as the eyes, ears, nose, and mouth. The 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 enable sound localization of the direction and distance of sounds. The skull also supports tendinous muscle attachments and allows neurovascular passage between intracranial and extracranial anatomy.