The fontanelle is the “soft spot” on the top of a newborn baby’s head. It is where the bones of the skull have not fully formed and allows the head to compress as it passes trough the birth canal. It is usually gone by the first birthday.
Here is a note from the chart of a baby I saw one night:
“Nineteen-day-old male had fontanelle sink in while driving up a hill last night. Mom placed her thumb in the child’s mouth and pressed up to push the fontanelle back up. States the baby is somewhat fussy.”
The parents were a young Hispanic couple and, apparently in their culture, there is an understanding that the fontanelle can “fall” if the child is ill. They believed that pushing up on the roof of the mouth can put it back in place, making the child well again.
My examination of the baby revealed nothing abnormal and he was sent home. Apparently, the mother’s quick action worked.