Skull Bones Anatomy Overview
Facial and Cranial Bones Anatomy
Introduction
The skull (cranium) is the skeletal structure of the head that supports the face and protects the brain. It is subdivided into the facial bones and the cranial bones. The facial bones underlie the facial structures, form the nasal cavity, enclose the eyeballs, and support the teeth of the upper and lower jaws. The cranial bones surround and protect the brain and house the middle and inner ear structures.
Twenty-two bones form the adult skull. Twenty-one are immobile and united into a single unit. The 22nd bone, the mandible, is the only movable skull bone.
Facial Bones
The facial bones (facial skeleton or viscerocranium) form the anterior portion of the skull and consist of 14 individual bones that create the framework of the face.
These bones form and protect the nasal cavity and paranasal sinuses, create the orbital cavities that house and protect the eyeballs, and support the teeth of the upper and lower jaws.
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The inferior nasal conchae are a pair of curved bony plates that project into the nasal cavity from the cavity’s lower lateral walls.
The lacrimal bones are a pair of small bones located on the medial wall of each orbit. Each lacrimal bone helps form the lacrimal fossa, which houses the lacrimal sac for tear drainage.
The mandible bone is a U-shaped bone that forms the lower jaw.
The two maxilla bones form the upper jaw, much of the hard palate, the medial floor of the orbit, and the lateral base of the nose.
The two palatine bones are L-shaped bones that form parts of the orbits, the nasal cavity, and the roof of the mouth (hard palate).
The vomer bone is a triangular bone that forms the posterior inferior part of the nasal septum.
The zygomatic bones are a pair of irregular-shaped bones that form the prominence of the cheeks and much of the lateral walls and floor of the orbits.
Cranial Bones
Eight cranial bones comprise the braincase (neurocranium), which encloses and protects the brain.
The rounded top of the braincase is called the calvaria, and the floor is called the skull’s base. The interior of the braincase is referred to as the cranial cavity.
The skull base is a complex region that varies in depth and contains numerous openings through which cranial nerves, blood vessels, and the spinal cord pass. Internally, the base is subdivided into three large depressions called cranial fossae (fossa = “trench or ditch”), each housing a different brain region.
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The ethmoid bone forms the roof and lateral walls of the upper nasal cavity and the upper portion of the nasal septum. It also contributes to the medial wall of the orbit. Within the skull, the ethmoid also forms part of the floor of the anterior cranial cavity.
The frontal bone forms the anterior part of the skull (forehead).
The occipital bone forms the posterior skull and posterior base of the braincase.
The two parietal bones form most of the upper lateral sides of the skull.
The sphenoid bone forms much of the skull’s central base and extends laterally to contribute to the sides of the skull.
The temporal bones are a pair of bones that form the lower lateral sides of the skull.
Assessment
Facial Bones Flip Card Quiz
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Cranial Bones Flip Card Quiz
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Terms of Use
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References and Attributions
OpenStax – “The Skull“. Access for free at – https://openstax.org/books/anatomy-and-physiology/pages/1-introduction
Wikipedia – “Facial Skeleton“.
Wikipedia – “Human Skull“.
Wikipedia – “Neurocranium“.