What is the function of the mastoid portion of temporal bones?

The mastoid portion of the temporal bone primarily serves to assist in the formation of the skull base. This region of the skull is involved in providing structural integrity and support to the cranial cavity, ensuring that the brain is protected and that the weight of the head is evenly distributed. The mastoid process itself extends behind the ear and contains air cells which help to reduce the weight of the skull while still providing a solid anchor point for muscles related to head movement.

While the mastoid portion is adjacent to areas involved in hearing, such as the inner ear and structures related to auditory functions, its main role is not to house those hearing structures directly. Rather, hearing structures are more closely associated with the petrous portion of the temporal bone.

Support for facial muscles and protection of the brain are generally functions associated with a broader range of cranial structures rather than specifically attributed to the mastoid portion alone.