Skull

The skull is the bony framework of the head, comprising the cranium and the facial skeleton. It protects the brain, supports the sense organs, and forms the openings for the airways and digestive tract. The skull also provides attachment points for muscles involved in facial expression and chewing.

In humans the skull consists of 22 bones: eight cranial bones (frontal, two parietal, two temporal, occipital, sphenoid, ethmoid) and fourteen facial bones (two nasal, two maxillary, two zygomatic, two lacrimal, two palatine, two inferior nasal conchae, vomer). The mandible, or lower jaw, is the largest facial bone but is not part of the skull proper, though it articulates with the skull at the temporomandibular joints. Joints between the skull bones are fibrous sutures that allow growth during infancy and childhood; in a newborn, fontanelles are soft spots where sutures intersect.

The skull's base forms a complex floor with foramina and canals that transmit nerves and vessels to the brain, face, and neck. The orbits house the eyes; the nasal cavity and oral cavity are bounded by the bones of the face and skull.

Developmentally, many skull bones arise through intramembranous ossification, while others form by endochondral ossification. Growth continues at sutures and fontanelles, with most cranial sutures fusing in late adolescence.

Clinical aspects include skull injuries such as fractures, and conditions like craniosynostosis, where one or more sutures fuse prematurely. Abnormal skull development can affect intracranial pressure, facial structure, and overall head morphology.