The skull consists of 23 bones of different sizes and shapes (not counting the three pairs of ossicles in the middle ear), which are divided into two parts: skull and facial skull. Except hyoid bone is free, mandible and temporal bone form joints, the rest are closely connected by suture, cartilage or bone combination, forming the bone foundation of cranial cavity and face, thus containing and protecting brain and sensory organs and forming the initial part of digestive and respiratory system.

The skull is divided into the upper skull and the lower skull by the boundary of the upper orbital margin, the upper auricular margin and the occipital protuberance.

Facial cranium

It consists of 15 bones: the unpaired bones are the vomer, mandible and hyoid bone, and the paired bones are the maxilla, palate, cheekbone, nasal bone, lacrimal gland bone and inferior turbinate bone.