It consists of 22 bones, of which 21 are immobile and united into a single unit
Skull — the 22nd bone is the mandible, the only movable bone.
Anatomy · Bones
Skull
22 bones, 21 of them immobile
Axial skeleton · head
The skull is the bony framework of the head. It protects the brain and supports the face, and it is made of 22 bones: 8 cranial bones forming the brain case and 14 facial bones. Apart from the mandible, all are locked together by immovable sutures. It sits on the atlas, the first vertebra of the spine.
How to spot them
- ▸The brain case (cranium) above and behind, with a face of orbits, nasal opening and jaws in front
- ▸Eight cranial bones: frontal, two parietal, two temporal, occipital, sphenoid and ethmoid
- ▸Fourteen facial bones, including the maxillae, zygomatic bones, nasal bones and mandible
- ▸Bones joined by fibrous sutures; only the mandible moves
What to know
Eight bones form its brain case: four single bones and two pairs
Skull — cranial bones: frontal, occipital, sphenoid, ethmoid (unpaired), parietal and temporal (paired).
Fourteen of its bones make up the face, including the two unpaired bones vomer and mandible
Skull — facial bones: maxilla, palatine, zygomatic, nasal, lacrimal, inferior nasal concha (paired), vomer, mandible.
It is divided into two portions: a neurocranium enclosing the brain, and a viscerocranium supporting the face
Skull — the cranium (roof and base) and the facial skeleton.
Inside, its floor is divided into three steps, the anterior, middle and posterior fossae, pierced by openings for nerves, vessels and the spinal cord
Skull — the cranial fossae.
Key ideas
- The neurocranium (cranial roof, or calvaria, plus base) encloses the brain, while the viscerocranium supports the face, orbits, nasal and oral cavities and sinuses.
- The 22 do not include the hyoid bone in the neck, nor the three tiny ossicles (malleus, incus and stapes) in each ear.
Quick-fire facts
- •22 bones: 8 cranial and 14 facial
- •Only the mandible is movable
- •The three cranial fossae: anterior, middle and posterior
- •The nasal bones are the most commonly fractured facial bones
- •Le Fort fractures classify fractures of the maxilla, graded 1 to 3
- •Sutures are immobile fibrous joints unique to the skull, and fuse around age 20 according to TeachMeAnatomy
- •The largest opening in the skull is the foramen magnum
- •Skull bones form by intramembranous ossification
Drill it — 8 cards
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Sources
- TeachMeAnatomy — Overview of the Bones of the Skull
- OpenStax — Anatomy and Physiology 2e, 7.2 The Skull
- Kenhub — The skull