SKULL SUTURES
At birth, the skull has openings (sutures) to accommodate brain growth, because the cranial vault ossifies early via intramembranous ossification. These sutures allow the fetal skull to ossify quickly prior to delivery [via intramembranous ossification] (so the brain doesn't get squashed) and yet still accommodate skull distortion during birth (called, molding) and permit rapid brain growth during the first two years of life when the brain quadruples in size to 75 percent of its adult volume!
Metopic - forms between midline aspects of the left/right aspects of the frontal bone.
Coronal - lies between the frontal and parietal bones.
Sagittal - lies between the bilateral parietal bones.
Lambdoid - lies between the parietal bones and occipital bone.
There are three additional minor sutures: frontonasal, temporosquamosal, and frontosphenoidal.
THE FONTANELLESThe large openings that exist in the newborn calvarium.
The frontal bone covers the majority of the anterior frontal lobes.
The parietal bones cover the remainder and the parietal lobes.
The occipital bone covers the occiput.
Anterior fontanelle
Forms at the junction of the sagittal, coronal, and metopic sutures at the anterior of the skull – it's palpable in midline, just behind the forehead; it closes at 1.5 to 2 years of age.
Posterior fontanelle
Forms from the intersection of the sagittal and lambdoid sutures; it closes at 3 - 6 months of age.
