Understanding Fontanels: What Are Fontanels Composed Of?

When it comes to having a newborn, there are many things to learn and understand. One of the unique and fascinating aspects of a newborn’s anatomy is their fontanels. These soft spots on their skull can often be both intriguing and concerning for new parents. But what exactly are fontanels composed of?

Fontanels are made up of a membrane and fibrous tissues, which connect the bones of a baby’s skull. The purpose of these soft spots is to allow for flexibility and easier delivery during childbirth. While they may seem concerning due to their delicate nature, fontanels are actually incredibly important for a baby’s growth and development.

As a parent, it’s important to understand what fontanels are composed of and how to properly care for them. Knowing what to look for and what is normal can help ease any concerns and ensure your baby is happy and healthy. So, let’s dive deeper into the fascinating anatomy of fontanels and discover why they are so unique to newborns.

The Anatomy of a Fontanel

A fontanel, also known as a soft spot, is an anatomical feature found on the newborn’s skull. These soft spots are areas where the bone has not yet fused together, and instead, a thin layer of tough membrane covers the gap. The fontanels allow the newborn’s brain to grow rapidly in size during the first year of life without compromising the skull’s structural integrity.

There are usually six fontanels on the newborn’s skull, with a combination of two types. The anterior fontanel is the largest and connects the two frontal and two parietal bones. The posterior fontanel is smaller and located at the back of the skull, where the occipital and parietal bones meet. The other four fontanels are located on the sides of the head, known as the sphenoid fontanels.

  • The anterior fontanel is diamond-shaped and measures about 2-3 cm in diameter at birth and usually closes around 18 months.
  • The posterior fontanel is triangular and, unlike the anterior fontanel, closes within eight weeks of birth.
  • The sphenoid fontanels are located on the sides of the head, and each measures no more than a centimeter in diameter.

During childbirth, the pressure exerted on the infant’s skull can lead to molding, which is the bone’s temporary reshaping. This process often results in a slightly elongated shape of the skull, which is normal and usually resolves within a few days or weeks.

It is normal for the fontanel to pulsate when the infant is crying or feeding, as the membrane covering the fontanel also encloses the underlying blood vessels and brain tissue. However, a bulging fontanel, especially when accompanied by other symptoms such as irritability or vomiting, may indicate an underlying medical condition that requires medical attention.

Types of Fontanels in Infants

Fontanels are the soft spots on a baby’s head where the skull bones have not yet fused together. These areas allow for the baby’s brain to grow and accommodate their rapidly increasing size. There are two main types of fontanels in infants: anterior and posterior fontanels.

  • Anterior Fontanel: The anterior fontanel is the larger of the two fontanels, located on the top of the baby’s head. It is diamond-shaped and usually measures between 2 and 3 cm in diameter. The anterior fontanel allows for the baby’s brain to grow rapidly during the first 18 months of life. It typically closes by 18-24 months of age.
  • Posterior Fontanel: The posterior fontanel is located near the back of the baby’s head, just above the neck. It is much smaller than the anterior fontanel and typically measures less than 1 cm in diameter. The posterior fontanel allows for the baby’s brainstem to develop and is crucial for the regulation of many bodily functions, such as heart rate and breathing. It usually closes by 2-3 months of age.

The Importance of Monitoring Fontanels

It is important to monitor the size and closure of fontanels to ensure proper brain development and growth. Abnormalities in fontanel size and closure can be an early indication of developmental issues or health concerns in the baby.

For example, a fontanel that is larger or smaller than normal for the baby’s age could indicate problems with brain growth or cranial pressure. A fontanel that remains open for too long past the normal time frame could also be a sign of developmental delays or underlying health conditions.

When to Consult a Pediatrician

If a fontanel appears unusually large or small, or if it does not close within the expected time frame, parents should consult with their baby’s pediatrician. The pediatrician may refer the baby to a specialist to further evaluate the issue and determine if any medical interventions are necessary.

Fontanel Type Location Typical Size Typical Closure Time
Anterior Fontanel Top of head 2-3 cm in diameter 18-24 months
Posterior Fontanel Near back of head, above neck Less than 1 cm in diameter 2-3 months

Understanding the different types of fontanels in infants, monitoring their size and closure, and consulting with a pediatrician when necessary can help ensure optimal growth and development for babies.

The Function of a Fontanel

A fontanel, also known as a “soft spot,” is a gap between the bones in a baby’s skull that hasn’t yet fused together. These soft spots feel like a slight depression, with a slightly different texture to the surrounding bone. In total, there are six fontanels on a baby’s skull, with the most prominent ones being the anterior fontanel, located at the top/front of the head, and the posterior fontanel, located at the back of the head.

The fontanels play an essential role in the development of a baby’s brain, providing the flexibility needed for the skull to shape and mold as the brain grows. Additionally, fontanels allow for easier passage of the baby’s head during birth, as they allow the skull to be compressed without causing injury to the brain.

Functions of Fontanels:

  • Brain Development: The fontanels provide the necessary flexibility for the baby’s skull to shape and mold as the brain grows, allowing it to expand and accommodate the rapid growth and development of the baby’s brain.
  • Birth: Fontanels allow for easier passage of the baby’s head during birth, as they allow the skull to be compressed without causing injury to the brain. They also make it easier for the baby’s head to be positioned correctly during delivery, reducing the risk of complications or injury.
  • Maintenance of Intracranial Pressure: The fontanels help regulate pressure within the baby’s skull. When the brain produces cerebrospinal fluid, the extra fluid can escape through the fontanels, thus preventing a buildup of pressure within the skull.

The Importance of Monitoring Fontanels:

Monitoring the fontanels is a crucial part of newborn care, as they can serve as an indicator of various medical conditions. A fontanel that is overly large or not closing as quickly as it should can be a sign of hydrocephalus, a buildup of fluid in the brain that can cause brain damage. A sunken or depressed fontanel might indicate dehydration or malnourishment. A bulging fontanel might indicate meningitis, a potentially life-threatening infection of the membranes surrounding the brain and spinal cord.


Function Description
Brain Development Provides flexibility for the baby’s skull to shape and mold as the brain grows
Birth Eases delivery by allowing the skull to be compressed without causing injury to the brain
Maintenance of Intracranial Pressure Helps regulate pressure within the baby’s skull

By understanding the functions of fontanels and monitoring them appropriately, caregivers can keep a watchful eye on a baby’s brain development, reduce the risk of complications during delivery, and detect any underlying medical conditions that may require prompt medical attention.

The Difference Between a Fontanel and a Suture

When it comes to the skull of a newborn baby, there are two main features that stand out: fontanels and sutures. While these two terms may seem interchangeable, they actually refer to two different structures in the skull that serve different purposes.

  • Fontanel: A fontanel is a space between the bones of a baby’s skull that is covered by a tough membrane. There are typically six fontanels in a newborn’s skull, although some may fuse together over time. The largest and most noticeable fontanel is located at the top of the skull and is known as the anterior fontanel.
  • Suture: A suture, on the other hand, is the joint between two bones in the skull. These joints are rigid and do not move, and they play an important role in keeping the skull strong and stable. Sutures fuse together over time, helping to form the rigid structure of the adult skull.

While fontanels and sutures may seem similar at first glance, they serve different purposes and have distinct characteristics.

One key difference between fontanels and sutures is their function. Fontanels are designed to allow the bones of the skull to move and shift slightly during birth, which helps the baby pass through the birth canal. They also provide room for the brain to grow and develop, and they are a key part of the flexible structure of a newborn’s skull.

Sutures, on the other hand, are designed to hold the bones of the skull together and provide stability and protection for the brain. They are strong, rigid joints that do not move, and they help to ensure that the skull remains a solid and protective structure throughout life.

Another key difference between the two structures is their appearance. Fontanels are visible as soft spots on a baby’s skull, while sutures are not visible to the naked eye. Fontanels have a distinctive appearance and texture, and they may feel slightly soft or “spongy” to the touch.

Fontanel Suture
Soft, flexible joint between bones Rigid joint between bones
All six fontanels close by 24 months of age Sutures gradually close during childhood
Visible as soft spots on a baby’s skull Not visible to the naked eye

In summary, fontanels and sutures are two distinct structures in the skull that play different roles. Fontanels are soft spots that allow for flexibility and growth, while sutures are rigid joints that provide stability and protection. Understanding these differences can help parents and caregivers better understand the development and structure of a newborn’s skull.

When Fontanels Close in Infants

Fontanels, the soft spots on a baby’s head, serve an important role in their development. However, at some point, these soft spots must close as the baby’s skull grows and develops. The timing of fontanel closure can vary from baby to baby, but there are some general patterns that can help parents and medical professionals understand what to expect.

Factors Affecting Fontanel Closure

  • Gender: Male infants tend to have later fontanel closure than female infants.
  • Genetics: The timing of fontanel closure can be influenced by a baby’s genes.
  • Size and birth weight: Babies with larger head circumferences or birth weights may have slower fontanel closure.

Normal Timeline for Fontanel Closure

The timeline for fontanel closure can vary, but the following is a general guideline for when fontanels typically close:

Fontanel Average Age of Closure
Anterior fontanel (largest fontanel at the top/front of the head) 12-18 months
Posterior fontanel (smaller fontanel at the back of the head) 2-6 months

It’s important to note that these are just averages, and some babies may experience closure earlier or later than these general guidelines.

Signs of Early or Late Fontanel Closure

In some cases, early or late fontanel closure may occur. If fontanels close too early, it may affect a baby’s brain development and cause issues such as developmental delays. Conversely, if fontanels close too late, it may indicate a medical issue such as hydrocephalus (an accumulation of cerebrospinal fluid in the brain).

If a parent or medical professional suspects abnormal fontanel closure, they should consult a pediatrician. Signs of abnormal closure may include:

  • Early closure: Poor brain growth, seizures, developmental delays.
  • Late closure: Increased head circumference, bulging fontanels, delayed motor development.

Keeping track of fontanel closure in babies is an important part of monitoring their growth and development. By understanding the normal timeline for fontanel closure and watching for signs of abnormal closure, parents and medical professionals can help ensure a baby’s healthy development.

Monitoring fontanel growth and development

One of the most important aspects of newborn care is monitoring the growth and development of their fontanels. Fontanels are the soft spots on a baby’s skull, where the bones have not yet fused together. There are generally two fontanels on a newborn’s skull, one at the top of the head and one at the back.

During the first couple of years of life, the fontanels gradually close as the bones of the skull fuse together. It is crucial to monitor these areas to ensure that they are closing at a normal pace, as delayed or abnormal growth can indicate an underlying issue.

  • Regular checkups: Pediatricians regularly monitor fontanel growth and development during routine checkups. By tracking their size and how quickly they are closing, doctors can identify any potential concerns early and take appropriate action.
  • Observation: Parents can also monitor their baby’s fontanels at home by observing their size and how they change over time. Changes such as bulging, excessive pulsating, or rapid closure could indicate a problem and should be reported to a healthcare provider immediately.
  • Diagnostic tests: In some cases, healthcare professionals may carry out further tests, like an ultrasound or CT scan, to investigate any issues with fontanel growth and development. These tests can help identify potential abnormalities or underlying conditions that may be impacting the growth of the fontanels.

Timely monitoring of fontanel growth and development is essential to ensure normal growth and early detection of potential problems. Parents and caregivers should work closely with their pediatricians to make sure that their baby’s fontanels are growing and developing normally.

Here is a table summarizing the expected growth and development of fontanels:

Fontanel Location Timeline Normal closure
Anterior fontanel Top of the head 2-3 years 18-24 months
Posterior fontanel Back of the head 2-3 months 2-4 months

It is important to note that every baby is unique, and fontanel growth and development may vary slightly between individuals. Regular monitoring and communication with healthcare professionals can help ensure that any concerns are identified and addressed promptly.

Potential complications related to fontanels

Fontanels, also known as soft spots, are the gaps between the bones in a baby’s skull that allow for growth and development of the brain. While fontanels usually close by the age of two, they can cause potential complications if not monitored and treated properly. Here are some of the potential complications related to fontanels:

  • Delayed or abnormal closure: The fontanels in a baby’s skull should close on schedule, but in some cases, they may close too early or too late. This can be a sign of an underlying medical condition that requires treatment.
  • Increased intracranial pressure: Fontanels play a role in regulating the pressure inside the skull. If the fontanels close too early or are not functioning properly, the pressure inside the skull can increase, leading to a range of symptoms including headaches, vomiting, and seizures.
  • Craniosynostosis: This is a condition where one or more of the sutures (the seams between the bones) in the skull fuse prematurely, causing an abnormal head shape and potential developmental delays.

In addition to these complications, there are also some conditions that can affect the fontanels themselves:

Hydrocephalus: This is a condition where there is an excess of cerebrospinal fluid (CSF) in the brain, which can cause the fontanels to bulge. Hydrocephalus can be caused by a range of underlying conditions, and treatment depends on the cause and severity of the condition.

Osteogenesis imperfecta: This is a genetic condition that affects the bones, including the fontanels. With osteogenesis imperfecta, the skull bones may be thinner and more fragile than usual, leading to potential complications.

If you are concerned about your baby’s fontanels or notice any changes in them, it is important to speak with a healthcare provider who can provide guidance and treatment as needed. With proper monitoring and treatment, most fontanel-related complications can be successfully managed.

What are Fontanels Composed of?

Q: What are fontanels?
A: Fontanels are the soft spots on a baby’s skull that have not yet fused together.

Q: What are fontanels composed of?
A: Fontanels are composed of a tough membrane called the cranial vault that is covered by skin.

Q: Is there a difference in composition between anterior and posterior fontanels?
A: Yes, the anterior fontanel is made up of four bones: two frontal bones and two parietal bones, while the posterior fontanel is composed of two parietal bones.

Q: How long does it take for fontanels to close?
A: Fontanels usually close by the time a baby is two years old.

Q: Are fontanels important?
A: Yes, fontanels are important because they allow the baby’s brain to continue growing and developing even after birth.

Q: Can fontanels be a sign of a medical condition?
A: In some cases, an unusually large or small fontanel can be a sign of a medical condition that requires medical attention.

Q: Can fontanels be touched or manipulated?
A: While it is safe to touch fontanels gently, they should never be manipulated or pushed.

Closing Thoughts

Now you know what fontanels are made of and why they are important for a baby’s development. As babies grow and develop, their fontanels will naturally close, allowing their skull to become fully formed. Thank you for reading and please visit us again for more informative articles.