Craniosynostosis - Cranial Sutures

Cranial Sutures

The mesenchyme above the meninges undergoes intramembranous ossification forming the neurocranium. The neurocranium consists of several bones, which are united and at the same time separated by fibrous sutures. This allows movement of the separate bones in relation to one another; the infant skull is still malleable. The fibrous sutures specifically allow the deformation of the skull during birth and absorb mechanical forces during childhood They also allow the necessary expansion during brain growth.

In the first years of life the sutures serve as the most important centers of growth in the skull. The growth of the brain and the patency of the sutures depend on each other. Brain growth pushes the two sides of the patent sutures away from each other, thereby enabling growth of the neurocranium. This means that the neurocranium can only grow if the sutures remain open. The neurocranium will not grow when the forces induced by brain growth are not there. This will occur for example when the intracranial pressure drops; the sutures do not experience stretch anymore causing them to fuse.

The infant's skull consists of the metopic suture, coronal sutures, sagittal suture, and lambdoid sutures. The metopic suture is supposed to close between three to nine months of age. The lambdoid, sagittal and coronal sutures are supposed to close between 22 to 39 months of age.