neurocranium

The neurocranium, or braincase, is the portion of the skull that encloses the brain and forms the cranial cavity. It is divided into two regions: the calvaria, or skull cap, which roofs the brain, and the cranial base, which forms the inferior floor of the cranial cavity. The bones contributing to the neurocranium are the frontal bone, the two parietal bones, the occipital bone, the sphenoid, and the ethmoid, with portions of the temporal bones contributing to the base and lateral walls of the skull.

Development occurs through two ossification processes. The calvarial bones largely arise by intramembranous ossification, while most of the cranial base forms by endochondral ossification within the cartilaginous chondrocranium. The neurocranium derives from a combination of neural crest- and paraxial mesoderm-derived tissues. Growth is facilitated by sutures between bones, such as the coronal, sagittal, and lambdoid sutures, which remain unfused in infancy and early childhood.

Functions include protecting the brain and its coverings, housing the meninges and intracranial vessels, and providing attachment sites for certain muscles and membranes. Clinical considerations involve craniosynostosis, a premature fusion of sutures that can alter skull shape and brain growth, and skull-base trauma or congenital anomalies affecting cranial development. Imaging assessments commonly employ computed tomography to evaluate bone detail and magnetic resonance imaging to assess brain and soft-tissue structures, aiding diagnosis and surgical planning.

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