The axial skeleton is the central axis of the osseous frame. It is made up of 69 bones, including the cranium, backbone and thorax. The cranium contains the cranial and facial bones, as well as the auditory ossicles. Further down we have the spine, which is the main pillar of our osseous structure. It is formed by the cervical, thoracic and lumbar vertebrae, in addition to the sacrum and the coccyx. Between the spine and sternum, surrounded by the ribs, we have the thorax, which is an essential part of the axial skeleton because it protects important organs, such as the heart and lungs.
Cranium
It protects the brain, eyes, ears and nose. It is made up of 23 bones, which form the cranial vault and the skeleton of the face.
The cranial vault contains eight bones, which fit into fixed joints called sutures.
– The frontal bone forms the forehead and contributes in shaping the eye sockets (space where the eyeballs are housed).
– Two temporal bones protect the canals that lead to the middle and inner ear.
– Occipital bone: it has an orifice that connects the cranium to the spine.
– Two parietal bones form the upper part and walls of the cranium.
– Ethmoid bone: it is located at the center of the cranium.
– Sphenoid bone: it contains the pituitary gland.
The spine
The spine is the main structural pillar of the human skeleton and it is formed by 33 bones called vertebrae. It begins in the cervical area and ends in the sacrum and coccyx. One of its main functions is protecting the spinal cord, because it contains the nerves that enable our body to move.
The cervical vertebrae are under the cranium; they allow for greater mobility. At the top of the back we have the dorsal vertebrae, which help hold the ribs. Further down are the lumbar vertebrae, which support most of the body’s weight; and beneath these vertebrae, we have the sacrum (the back part of the pelvis).
At the final stretch of the spine we encounter the coccyx, a small bone that fits beneath the sacrum.
