When Does the Fontanelle Close?

A newborn baby can look quite unlike the cherub usually seen in the media. The head looks misshaped, the skin is blotchy and the wrinkles many in number. 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 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.

What is the Fontanelle?

The skull of a baby is made up of six different bones that are held together by a flexible, elastic tissue called 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, thereare soft places where the bones are not quite knit togethe. 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 m astoid 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 a nterior 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 her second birthday.

The p osterior 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 s phenoid and m astoid fontanelles also close up within a couple of months after birth of the baby. They are not too large to begin with so are not noticed by most parents as soft spots on the baby’s skull.

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 the flatness appearing on the side of the head is referred to as brachycephaly.

The appearance of this flatness is directly related to the position the baby’s lead 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 favourite 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.

Reviewed by Catherine Shaffer, M.Sc.

References

  1. Medline Plus, Cranial Sutures, https://medlineplus.gov/ency/article/002320.htm
  2. BabyCenter, Soft Spots, http://www.babycentre.co.uk/x552709/what-are-the-soft-spots-on-my-newborns-head
  3. American Family Physician, The Abnormal Fontanelle, http://www.aafp.org/afp/2003/0615/p2547.html
  4. Kidshealth, http://kidshealth.org/en/parents/newborn-variations.html

Further Reading

Last Updated: Jan 29, 2017

Advertisement

Comments

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News-Medical.Net.
Post a new comment
Post