What’s an anterior fontanel?

The anterior fontanel, or soft spot on a baby's skull, is a cause of concern for many parents. Elsewhere, the baby's brain is protected by a wall of bone; here only soft, squishy tissue separates the brain from the traumas of the outside world. The soft spot seems so vulnerable. I spoke with a mother today who had never touched her son's soft spot -- she was afraid she would put her finger through it.

In truth, the soft spot is another example of the amazing design of the human body. At birth there are six soft spots, but only two are noticeable (the largest, up on top, is the anterior fontanel). The loose connections of the skull bones that intersect in the soft spots make labor and delivery possible. Without this flexible anatomy, either human babies would have to have smaller brains or human mothers would have to have wider hips if any babies were to be born.

The value of the soft spot isn't gone when you first hold your baby in your arms. Far from making the baby more vulnerable, the soft spot protects a baby from injury. True, it makes some uncommon accidents more dangerous (landing head first on top of a car's radio antenna), but for the common falls experienced by all babies, the soft spot cushions and protects -- making the skull function rather like a football helmet.

Every week, frantic parents rush into my office after their babies have fallen off a bed or table or highchair. It happens so quickly, babies can fall even with careful and attentive parents -- it's even happened to me, but don't tell :^). When babies fall, they usually land head first, since their centers of gravity are in their heads (adults' centers of gravity are in our bottoms). The head hits the floor with a terrible, ripe-melon-like "thwunk." Thanks to the cushioning of the soft spot, most of these head injuries are quite minor. And by the way, although the spot is soft, it actually consists of a surprisingly tough fibrous membrane. Next time you visit with your child’s doctor, ask them to help you feel this amazing structure.