In the newborn |skull|, the |occipital bone| and |parietal bones| are not yet solidly sutured. Between these bones is located a cartilaginous membrane, called the posterior fontanelle. In the newborn, this ~cartilage~ is still quite flexible, allowing the |skull| to deform and articulate slightly during |childbirth|. The posterior fontanelle does not close completely, forming the intersection between the lambdoid and sagittal sutures, until the second or third month of life.