what is fontanelle

A fontanelle is the soft spot on a baby’s skull where the bone plates have not yet fully fused together. It helps the skull flex during birth and gives the brain room to grow after birth.

Simple meaning

• It is a gap covered by tough membrane, not an open hole.

• Babies usually have two main fontanelles: one at the top/front and one at the back.

• The front one is the larger and usually closes later, often by around 18 months.

Why it matters

• It supports normal skull and brain growth in infancy.

• Doctors check it during baby exams because a fontanelle that is bulging or sunken can sometimes signal a health issue.

• A gentle pulse can be normal.

Example

If you feel a soft, slightly springy area on the top of a newborn’s head, that is the fontanelle.

Word origin

The word comes from Old French and is related to the idea of a small spring or fountain.