Sutures
From the side the cranium shows a few large plates: the frontal bone of the forehead, the two parietal bones of the roof, the occipital bone at the back, a temporal bone over each ear and the sphenoid, which crosses the base of the skull from side to side.
The skull from the side, with the coronal and squamosal sutures, Gray's Anatomy, 1918, figure 188Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray188.png)
The plates meet at sutures, wavy joints filled with a thin layer of fibrous tissue. The coronal suture crosses the top of the head between the frontal and parietal bones. The sagittal suture runs between the two parietal bones, and the lambdoid suture between them and the occipital bone.
The sutures let the skull grow with the brain. In adults they slowly fill with bone, at ages that vary widely. If a suture closes too early in a baby, a condition called craniosynostosis, the skull grows out of shape.
The bones of the skull from the side, each in its own colourWikimedia Commons, Mariana Ruiz Villarreal (LadyofHats), Public domain (Human skull side simplified (bones).svg)
Sources
- Susan Standring (ed.), Gray's Anatomy, 42nd ed. (2020), chapter on the skull.
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