A suture is a type of fibrous joint which only occurs in the skull (or "cranium"). The bones are bound together by Sharpey's fibres. A tiny amount of movement is permitted at sutures, which contributes to the compliance and elasticity of the skull. These joints are synarthroses. It is normal for many of the bones of the skull to remain unfused at birth. The fusion of the skull's bones at birth is known as craniosynostosis. The term "fontanelle" is used to describe the resulting "soft spots". The relative positions of the bones continue to change during the life of the adult (though less rapidly), which can provide useful information in forensicsand archaeology. In old age, cranial sutures may ossify (turn to bone) completely. The joints between the teeth and the joint between the mandible and the cranium, the temporomandibular joint, form the only non-sutured joints in the skull.