The bones of the head and neck play the vital role of supporting the brain, sensory organs, nerves, and blood vessels of the head and protecting these structures from mechanical damage. Movements of these bones by the attached muscles of the head provide for facial expressions, eating, speech, and head movement.
The skull consists of 22 cranial and facial bones, which, with the exception of the mandible, are tightly fused together. The skull encases and protects the brain as well as the special sense organs of vision, hearing, balance, taste and smell. Attachment points for the muscles of the head and neck are located on the exterior surfaces of the skull and allow for important movement like chewing, speech, and facial expressions. Teeth are rooted into deep sockets in the mandible and maxillary bones. The upper portions of the digestive and respiratory tracts are also housed within the hollow oral and nasal cavities of the skull.
Another important bone of the head and neck is the hyoid bone. The hyoid is closely associated with the skull but is a “floating bone” that does not form a joint with any other bone. It anchors muscles of the tongue and throat and holds open the larynx of the respiratory tract. The auditory ossicles (malleus, incus, and stapes) of each ear are also bones in the head separate from the skull. They form a bridge connecting the eardrum to the inner ear and function to transmit vibrations between these parts.
The 7 cervical vertebrae form the bones of the neck that support the skull and organs of the head. The first cervical vertebra (atlas) supports and balances the head. The second vertebra (axis) allows the head to rotate laterally to the left and the right. Hollow spaces within the cervical vertebrae protect and conduct the spinal cord and vertebral arteries through the neck. Muscle attachment sites on the cervical vertebrae provide movement and posture to the head and neck.