fontanel /fon′tənel″/ [Fr, fontaine, fountain] , a space covered by tough membranes between the bones of an infant’s cranium. The anterior fontanel, roughly diamond-shaped, usually closes between the ages of 12 and 18 months. The posterior fontanel, triangular in shape, closes about 2 to 3 months after birth. Increase in intracranial pressure may cause a fontanel to become tense or bulge, as evidenced in infection such as meningitis. A fontanel may be soft and depressed as a result of dehydration. Also called fonticulus. Also spelled fontanelle.
