Skull

Skull
Volume rendering of a mouse skull
Details
System	Skeletal system
Identifiers
MeSH	D012886
FMA	54964
Anatomical terminology [edit on Wikidata]

The skull is a rigid osteocartilaginous enclosure around the brain^[1] at the rostral (head) end of a vertebrate's body. In jawed vertebrates, the skull comprises two prominent parts: the cranium (pl.: craniums or crania) and the mandible,^[2] which evolved from the first gill arch pair. The skull forms the frontmost portion of the axial skeleton and is a product of cephalization and vesicular enlargement of the brain, with several special senses structures such as the eyes, ears, nose, tongue and specialized tactile organs such as barbels.^[3]

The skull is composed of three types of bone: cranial bones, facial bones and ossicles, which is made up of a number of fused flat and irregular bones. The cranial bones are joined at firm fibrous junctions called sutures and contains many foramina, fossae, processes, and sinuses. In zoology, the openings in the skull are called fenestrae, the most prominent of which is the foramen magnum, where the brainstem goes through to join the spinal cord.

In human anatomy, the skull is separated into two parts: the neurocranium (a.k.a. the "braincase"), which is further divided into the calvarium and the endocranium, together forming a cranial cavity that houses the brain, with the interior periosteum forming part of the dura mater; and the viscerocranium, which consists of the bony facial skeleton and the cartilaginous visceral skeleton, with the mandible being its largest bone. The mandible articulates with the temporal bones (part of the neurocranium) at the paired temporomandibular joints. The skull itself articulates with the spinal column at the atlanto-occipital joint.

Functions of the skull include physical protection for the brain, providing attachments for neck muscles, facial muscles and muscles of mastication, providing fixed eye sockets and outer ears (ear canals and auricles) to enable stereoscopic vision and sound localisation, forming nasal and oral cavities that allow better olfaction, taste and digestion, and contributing to phonation by acoustic resonance within the cavities and sinuses. In some animals such as ungulates and elephants, the skull also has a function in anti-predator defense and sexual selection by providing the foundation for horns, antlers and tusks.

The English word skull is probably derived from Old Norse skulle,^[4] while the Latin word cranium comes from the Greek root κρανίον (kranion). The human skull fully develops two years after birth.