and ears; six are ear bones. With the exception of the lower jaw bone (mandible) and the ear bones, all skull bones are joined together and fixed in one position. The seams where they join are known as sutures.

Cranial Bones.— The cranium is formed by eight cranial bones, six of which are essential to know. The FRONTAL BONE, which forms the forehead, contains the frontal sinuses and helps form the eye socket and nasal cavity. The two PARIETAL BONES form the roof of the skull. The two TEMPORAL BONES, which help form the sides and base of the skull, also house the auditory, or hearing organs. The OCCIPITAL BONE forms part of the base and back of the skull and contains a large hole, called the FORAMEN MAGNUM. This opening permits passage of the spinal cord from the cranium into the spinal column.

Facial Bones.— The two MAXILLARY BONES form the upper jaw, nasal walls, and part of the eye socket. These bones contain large cavities called maxillary sinuses. Frequently these sinuses become infected, causing the individual much discomfort. The lower jaw is called the MANDIBLE. Its main function is mastication. Other bones of the face are the LACRIMAL and NASAL BONES.