The axial skeleton is the core part of the endoskeleton made of the bones of the head and trunk of vertebrates.

This article mainly deals with the axial skeletons of humans; however, it is important to understand its evolutionary lineage.

In humans, the axial skeleton serves to protect the brain, spinal cord, heart, and lungs.

The cranium holds and protects the brain in a large space called the cranial vault.

The cranium is formed from eight plate-shaped bones which fit together at meeting points (joints) called sutures.

In addition there are 14 facial bones which form the lower front part of the skull.

Together the 22 bones that compose the skull form additional, smaller spaces besides the cranial vault, such as the cavities for the eyes, the internal ear, the nose, and the mouth.

During development the eight separate plates of the immature bones fuse into one single structure known as the skull.