The cranial sutures appear as thin squiggly lines or “zipper-like articulations” (White & Folkens 2005) and are the fibrous, immovable, joints connecting the individual bones of your skull. For example, the coronal suture (see image to the right) is the joint between the frontal bone and the two parietal bones. You can also see the squamosal suture between the parietal and the temporal bone. Areas where sutures meet can be important landmarks for both bioarchaeologists and radiologists.

When you are born your cranium is obviously not at its full size. Instead, the bones are separated by fontanelles, soft membranes which permit the bones to flex through the birth canal and then allow postnatal growth before later ossification (see image below). The posterior fontanelle is closed by 1 year after birth while the anterior fontanelle is finished closing by about 18 months. Occasionally a suture will close prematurely before growth can finish; this condition is called craniosynostosis, and most commonly affects the sagittal suture between the two parietal bones. A surgical intervention involves reopening the suture so the bones can continue growing.

That’s all for the sutures, the immovable joints of your skull. Tomorrow we’ll talk about the viscerocranium – the facial skeleton.

REFERENCES & MORE TO EXPLORE

Cranial sutures. Sieroslawska KenHub Anatomy. Last reviewed October 2020

Major Sutures of the Skull. GetBodySmart. 2020

The Human Bone Manual. White & Folkens. 2005