Human cranium

Human cranium

File:Human skull side simplified (bones).svg
Lateral view of the human cranium
Latin	Cranium humanum
Precursor	Neural crest
System	Skeletal system

The human cranium is a complex bony structure that forms the head in the human skeleton. It serves as a protective case for the brain and supports the structures of the face. The cranium is part of the human skull, which also includes the mandible, or lower jaw.

Structure

The human cranium is composed of eight bones, which are fused together in adults. These bones are:

• Frontal bone - forms the forehead and the upper part of the eye sockets.
• Parietal bones (2) - located on the sides and roof of the cranium.
• Temporal bones (2) - situated at the sides and base of the skull, housing the structures of the ears.
• Occipital bone - forms the back and base of the skull, containing the foramen magnum.
• Sphenoid bone - located at the base of the skull, contributing to the floor of the cranial cavity.
• Ethmoid bone - a light, spongy bone located between the eyes, forming part of the nasal cavity.

These bones are connected by sutures, which are fibrous joints that allow for growth during development and fuse completely in adulthood.

Function

The primary function of the cranium is to protect the brain from injury. It also provides attachment points for muscles of the head and neck and supports the structures of the face. The cranium houses the cranial cavity, which contains the brain, meninges, and cerebrospinal fluid.

Development

The cranium develops from the neural crest cells and mesoderm during embryogenesis. The bones of the cranium are initially separated by fontanelles, which are soft spots that allow for growth of the brain and skull during infancy. These fontanelles gradually ossify and close as the child grows.

Clinical significance

The cranium can be affected by various medical conditions, such as:

• Craniosynostosis - a condition where one or more of the cranial sutures fuse prematurely, affecting skull shape and brain development.
• Fractures - trauma to the skull can result in fractures, which may lead to brain injury.
• Hydrocephalus - a condition characterized by an accumulation of cerebrospinal fluid within the cranial cavity, leading to increased intracranial pressure.

Also see

• Human skull
• Facial skeleton
• Cranial nerves
• Skeletal system
• Neurocranium