Normally, the bones of the skull are not joined at birth, allowing the head to grow evenly. In individuals with craniosynostosis, the sutures where the skull bones meet have closed, or close prematurely. As a result, the expanding skull bones grow abnormally, and the abnormal skull shape becomes more pronounced as the infant grows. The shape is dependent on which sutures have closed, and various abnormalities have specific names.
Acrocephaly, oxycephaly, turricephaly denote a pointed (high) head, caused by the premature closure of all sutures.
Brachycephaly denotes an abnormally short, squat skull, caused by the premature closure of the two coronal sutures, which cross the top front portion of the skull, width-wise.
Dolichocephaly and scaphocephaly denote an abnormally long front-to-back distance of the skull, caused when the sagittal suture, which runs lengthwise along the top of the skull, is closed.
Plagiocephaly denotes a somewhat lopsided, asymmetric, pointed appearance, caused by premature closure of sutures that cross the top of the skull widthwise (coronal sutures in the front, lambdoidal sutures in the back), on only one side.
Trigonocephaly denotes a triangular shape at the top of the skull, caused by the closing of the metopic suture, which runs lengthwise along the top front of the skull, forward of the sagittal suture and anterior fontanelle (the "soft spot" at the top front portion of an infant's skull).