Simple dolichocephaly is due to synostosis of the sagittal, or antero-posterior suture of the skull.
Pachycephaly (thickness of head) is due to synostosis of the parietal bone with the occipital.
As a result, osseous solidification of the joint (synostosis) ensues without, of course, the possibility of any movement.
This process of synostosis begins from the interior of the cranium, and only subsequently manifests itself externally.
Tapeisocephaly (low head) is due to synostosis of the great wings of the sphenoid with the frontal.
synostosis syn·os·to·sis (sĭn'ŏ-stō'sĭs)
n. pl. syn·os·to·ses (-sēz)
Fusion of normally separate bones. Also called bony ankylosis, true ankylosis.