In the Netherlands between 179.000 and 204.000 children were born annually during the
last ten years. Congenital anomalies occur in 1 in 33 births. Th e most frequent anomaly
involves the heart with a prevalence of 1 in 150 births (66.7 per 10.000 births). Th e ventricular
septal defects occur the most frequent (30.0 per 10.000 births) (Central Bureau
of Statistics Netherlands, European Registration of Congenital Anomalies, National
Neonatology Registration). A rare congenital anomaly is craniosynostosis, affecting 1 in
2.500 births.
Th e newborns cranial vault is composed of seven individual bones separated by sutures.
Th is arrangement accommodates transient skull distortion during birth and permits
future growth of the brain, the volume of which quadruples during the fi rst two years
of life. Th ere are six major cranial sutures: the metopic, two coronal, the sagittal, and
two lambdoid sutures. Six additional sutures are considered minor: two frontonasal, two
temporosquamosal, and two frontosphenoidal. At the anterior of the skull, the sagittal,
coronal, and metopic sutures meet to form the anterior fontanelle. Th e posterior fontanelle
is formed by the intersection of the sagittal and lambdoid sutures. The sutures function
as growth centres. In the center of a suture lie undiff erentiated, proliferating cells. A part
of these cells undergo osteogenic diff erentiation and migrate to the borders of the bone
sheets. After diff erentiation in osteoblasts growth of the sheets occurs by apposition.
At two months of age, the posterior fontanelle closes, followed by anterior fontanelle
closure at approximately two years of age. While the metopic suture typically closes within
the fi rst year of age, all remaining cranial sutures close in adulthood, although they are no
longer involved in skull growth after approximately the age of six. Th en skull growth takes
place by apposition of bone at the outer side of the skull and resorption at the inner side.
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