Which structure is NOT part of the skull base?

The maxilla is not considered part of the skull base because it is primarily involved in the formation of the facial skeleton rather than the cranial base. The maxilla forms the upper jaw and holds the upper teeth, as well as contributing to the orbits and nasal cavity. In contrast, the skull base is comprised of several bones that support the brain and form the floor of the cranial cavity: the frontal bone, temporal bone, and occipital bone are all significant components of the skull base. The frontal bone forms the forehead and the upper part of the orbits, the temporal bones house structures like the inner ear, and the occipital bone is located at the back and base of the skull, containing the foramen magnum where the spinal cord exits the skull. Each of these bones contributes to the protective and structural framework necessary for the organ they encase—namely, the brain.