When Does the Fontanelle Close?

A newborn baby can look quite unlike what is usually seen in the media. The head looks misshaped, the skin is blotchy and there are many wrinkles. However, within a few days, the features begin to change and the baby begins to look like a tiny version of the parents.

The one part of the baby that still requires care is the fontanelle. Fontanelle, also spelled fontanel, is derived from the Latin term fonticulus as well as the Old French word fontaine, which means fountain or little spring. The presence of the fontanelle is essential for the protection and proper development of the baby’s brain.

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What is the fontanel or fontanelle?

The skull of a baby is made up of six different bones that are held together by a flexible, elastic tissue called a suture. There is one frontal bone, one occipital bone, two parietal bones and two temporal bones. Sutures are present along the edges of all six bones and hold them together to form the cranium.

When you feel along a baby’s skull, there are soft places where the bones are not quite knit together. These soft areas are called the fontanelles. They are bordered by the suture lines which will eventually close and produce a solid skull.

If the sealing of the suture is done along the sagittal suture that runs the length of the skull, a long and narrow head is produced. Should the permanent seal take place along the coronal suture, which tends to run from side to side on the skull, it will produce a short and wide-shaped head.

Different types of fontanelle in newborn babies

When the six skull bones are bound by suture lines, six fontanelles are formed along them. The two primary fontanelles are the a nterior fontanelle and posterior fontanelle. The anterior fontanelle is found between the frontal bone and parietal bones. The posterior fontanelle is located between the pair of parietal bones and the occipital bone.

In addition to these two larger-sized fontanelles, there are four smaller fontanelles along the sutures of the remaining bones. Two are known as sphenoid fontanelles and the remaining two are called mastoid fontanelles.

The sphenoid fontanelles are on the front side of the skull between the sphenoid bone and the parietal bone. The mastoid fontanelles are found between the temporal bone and the occipital bone. This fontanelle lies towards the rear of the skull.

Time taken after birth for the fontanelles to close

The anterior fontanelle takes the longest time after birth to close. It will take between 12 to 18 months for the sutures to solidify here. The fontanelle is usually closed by the time the baby completes its second birthday.

The posterior fontanelle closes much earlier. By the third month after the baby’s birth the soft spot on the rear of the skull is usually sealed up as the suture knits the bones together. As the suture solidifies, the back of the skull is closed completely.

The sphenoid and mastoid fontanelles also close up within a couple of months of the birth of the baby. They are small and so are not noticed by most parents as soft spots on the baby’s skull.

Skull fontanelles

Precautions to take while fontanelles are open

The soft bones and flexible sutures can cause the head of the baby to flatten out. Should the flat area appear at the back of the head it is known as plagiocephaly, while if the flatness appears on the side of the head it is referred to as brachycephaly.

The appearance of this flatness is directly related to the position the baby’s head lies in when he sleeps. Parents should encourage the baby to sleep on the back and when awake to rest the rounder part of her head on a pillow. A rolled-up towel or a pillow in the shape of a doughnut may also be used to take the weight off the bones.

To get the baby to look from one side to the other, change the position of a favorite toy. As the neck muscles grow stronger make him lie on his stomach. As the baby grows older and can turn his head and sit up the pressure on the skull will decrease and the flatness will round out into a regular skull shape.

Should the shape of the head still appear abnormal after the baby has reached the toddler stage, discuss it with the doctor. He may perform a physical examination of the fontanelles to see if there is any development issue with the cranial bones. Should a problem exist a physiotherapist may be able to help correct it.

References

Further Reading

Last Updated: Mar 31, 2021

Cashmere Lashkari

Written by

Cashmere Lashkari

Cashmere graduated from Nowrosjee Wadia College, Pune with distinction in English Honours with Psychology. She went on to gain two post graduations in Public Relations and Human Resource Training and Development. She has worked as a content writer for nearly two decades. Occasionally she conducts workshops for students and adults on persona enhancement, stress management, and law of attraction.

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