schedel

Schedel is the bony case of the head that encloses the brain and supports the facial skeleton. It comprises 22 bones in the adult: eight in the cranium (neurocranium) and fourteen in the face (viscerocranium). The cranial bones are the frontal; two parietal; two temporal; occipital; sphenoid; and ethmoid. The facial skeleton includes the mandible; maxillae (two); zygomatic bones (two); lacrimal bones (two); nasal bones (two); palatine bones (two); inferior nasal conchae (two); and the vomer.

These bones are joined by fibrous sutures, such as the coronal, sagittal, lamdoid and squamous sutures. In infants several sutures remain unfused and fontanelles (anterior, posterior, sphenoidal and mastoid) permit growth of the brain and skull.

Anatomically the skull is divided into the calvaria (the roof and walls) and the cranial base. The base lies at the inferior skull and contains the anterior, middle and posterior cranial fossae, with foramina that transmit cranial nerves and vessels.

Developmentally, most calvarial bones form by intramembranous ossification, while skull base bones form mainly by endochondral ossification. Growth of the brain drives widening of the sutures and fontanelles during infancy, allowing the skull to accommodate increasing brain volume.

Functions of the skull include protection of the brain and sense organs, support for the facial skeleton, and attachment for muscles of mastication and facial expression. Some skull bones contain air-filled sinuses that lighten weight and influence voice resonance.

Clinical relevance includes skull fractures (linear, depressed, basilar) and craniosynostosis (premature suture fusion). Imaging such as CT or MRI is used to assess injury and pathology.