The human skull is composed of two distinct parts known as the neurocranium and viscerocranium.

Neurocranium

The neurocranium consists of bones that surround and encase the brain and sensory organs connected to the brain. Therefore, the neurocranium is also known as the braincase.

The space found within the neurocranium is known as the cranial cavity, and the brain and meninges mostly occupy it. Overall, the neurocranium is formed by eight bones.

The neurocranium can be further subdivided into two portions:

• Calvaria - the curved dome-shaped roof that covers the cranial cavity and structures found within it; it is also known as the skullcap or cranial vault; it is robust and mainly formed by the parietal bones, frontal bone, and occipital bone; however, small portions of the temporal bone (squamous part) and sphenoid (greater wings) also contribute;
• Cranial base - this part forms the lower aspect of the neurocranium and the floor of the cranial cavity and is further subdivided into the internal cranial base and the external cranial base; it is formed by the temporal bones, sphenoid, ethmoid, frontal bone, and occipital bone.

The primary function of the neurocranium is to give form and shape to the head and to protect the brain and structures found within the cranial cavity. The neurocranium forms the skeletal framework for the cranial cavity and orbital cavities, as well as provides attachment sites for numerous muscles and ligaments.

Viscerocranium

The viscerocranium is the part that is situated anterior to the neurocranium, and it is also known as the splanchnocranium. Overall, the viscerocranium is a collection of bones that defines the facial skeleton and supports the soft tissue of the face. It is formed by fourteen bones, excluding the hyoid bone.

The viscerocranium not only supports the soft tissue of the face and gives it its characteristic shape but also provides a skeletal framework for the nasal cavity, oral cavity, and orbital cavities, as well as contributes to the upper and lower jaws. Additionally, it provides attachment sites for numerous muscles. Moreover, the maxillae and mandible accommodate the teeth.