neurokranium

Neurokranium, also known as the braincase, is the portion of the skull that encloses and protects the brain in vertebrates. It is equivalent to the neurocranium and is distinct from the facial skeleton, which supports the sense organs and the mouth.

The neurocranium is traditionally divided into two parts: the calvaria (skull cap) and the base of the skull. The calvaria consists mainly of the frontal, parietal, and occipital bones. The cranial base comprises the sphenoid, ethmoid, temporal, and occipital bones and forms the anterior, middle, and posterior cranial fossae, with openings such as the foramen magnum that allow passage of nerves and vessels.

Developmentally, the bones of the neurocranium exhibit different ossification patterns. In humans, most of the calvaria forms by intramembranous ossification, while the cranial base forms by endochondral ossification. Growth is most rapid in infancy and childhood, aided by sutures in the calvaria and fontanelles that permit skull expansion to accommodate the growing brain.

Functionally, the neurocranium provides a rigid protective enclosure for the brain and supports the orbital and nasal cavities. It also serves as an attachment site for muscles involved in jaw movement and head and neck actions, and its shape influences the overall appearance of the face.