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Anatomy of a Skull

The skull of a human is composed of a set of over 20 individual bones, most of which are shared across many mammals but in different proportions and sizes. The major objective of the skull bone is to provide structural support for the brain, the mouth and the other important functions of the head.

  1. The Skull

    • A skull consists of the cranium, facial bones and mandible. These are all part of the axial skeleton, which, along with the vertebral column and sternum, are associated with the central nervous system. The cranium is the largest part of the skull and forms the braincase. The facial bones help form the nose, the eyes and the upper jaw and connect to the mandible. All of these bones are sutured together except the mandible.

    The Frontal Bone

    • The bone that covers the entire forehead is called the frontal bone. Its major features are the supra-orbital ridges, also known as brow ridges, just above the eye and a median sagittal crest that internally separates the two frontal hemispheres of the brain.

    The Middle Cranium

    • The frontal bone is connected to two parietal bones that cover the large, bulbous area of the cranium that projects all the way to the back and the sphenoid bone, which is a single bone that runs across the length of the face from side to side, joining together the cranium to the facial bones. The sphenoid bone vaguely resembles the shape of a butterfly and has two sinus passages where the nose should be.

    Back of the Cranium

    • The sphenoid bone is connected to two temporal bones running to the back of the head. These temporal bones are situated just beneath the parietal bones. The two temporal bones and two parietal bones all converge at a single bone in the back of the skull called the occipital bone. The foramen magnum is an opening in the occipital bone through which the cranial cavity communicates with the vertebral canal.

    The Face and Mandible

    • The facial structure contains two zygomatic (cheek) bones, the lacrimal, which forms a portion of the medial wall of each eye orbit, and the maxilla, which forms the upper teeth and jaw. Furthermore, the nose is composed of many small bones like the nasal bones, the palatines, the inferior nasal conchae and the ethmoid, which is at the roof of the nose and separates the nasal cavity from the brain. The vomer bone divides the nasal passages and connects to the ethmoid. The final two bones are the mandibles (the lower jaw) and the hyoid bone, which is shaped like a horseshoe and is situated between the chin and thyroid cartilage.

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