Skull

The skull (TA: cranium) is the superior-most part of the human skeleton and houses the brain and includes the skeletal elements of the face. It consists of numerous bones connected to each other by sutures which renders them immobile.

Terminology

Variability in which bones to include and how to count them exists. Most frequently, 22 bones are considered to form the skull. This excludes the three ossicles in each middle ear but includes the mandible.

According to the Terminologia Anatomica the mandible is not, however, technically considered part of the skull but is an extracranial bone of the head ¹. Generally, however, it is often included ².

Furthermore, some bones, most notably the maxilla and frontal bones, are variably counted as single or paired.

Gross anatomy

All of the skull's bones (except the mandible and ossicles) are connected to each other by sutures, a type of fibrous joint. This renders them immobile and forms a single rigid unit perforated by numerous foramina and fissures to allow the ingress and egress of arteries, veins, and nerves.

The skull is broadly divided into the rounded hollow part that houses the brain (neurocranium) and the part anteroinferiorly which forms the basis of the face and to which the areodigestive tract is attached (viscerocranium). Some bones contribute to both, but generally they are appropotioned as follows:

• neurocranium (further divided into calvaria (skull vault) and skull base)

  • ethmoid bone (unpaired)

  • frontal bone

  • occipital bone (unpaired)

  • parietal bone

  • sphenoid bone (unpaired)

  • temporal bone

• viscerocranium: facial bones

  • inferior nasal concha

  • lacrimal bone

  • mandible (unparied)

  • maxilla

  • nasal bone

  • palatine bone

  • vomer (unpaired)

  • zygomatic bone