The role and functions of the fontanel
In the first weeks after birth, the baby has 6 main fontanelles on the head:
- front;
- left and right wedge-shaped;
- symmetrical mastoid;
- rear.
During passage through the mother's birth canal, they help change the shape of the skull: after compression, the head passes easily, reducing the risk of hematomas and damage. The small exposed areas are made up of soft, membranous tissue that is covered with a thin layer of fat called skin. Such movable membranes temporarily replace durable seams.
The soft structure of the fontanel allows the bones of the skull to expand. Their main functions:
- help to avoid complications with increased intracranial pressure in an infant due to congenital pathologies, birth injuries;
- reduce the temperature in the body during illness, hot weather, protect the brain from overheating;
- allow the cranium to quickly increase in volume as the child grows;
- act as a shock absorber during impacts and falls.
At birth, the windows have a wedge or diamond shape, the standard size is from 6 to 30−35 mm.
Normally, small fontanels with an area of up to 20 mm can heal within a few weeks. They gradually ossify, turning into strong seams, invisible under the skin.
Features of the fontanelle in children
The bones of a newborn's skull increase as the brain grows. Active changes occur within a period of up to 2 years. At this time, they are fully formed. The fontanelle may well close quickly, much earlier than the deadline. However, this does not mean that the bones will stop growing.
The main function of the fontanel is to give the baby’s skull bones the correct position. This allows the baby to pass through the birth canal. After birth, children have an unusual head shape. The fontanel protects the baby from various injuries that can cause severe harm to the child’s health.
The functions of the fontanelle also include thermoregulation of the child. Babies may overheat or become hypothermic because heat removal processes have not yet been developed. In addition, parents are often overzealous with wrapping their child.
Norms of a large fontanel
Large fontanelle
After birth, the baby remains open with two translucent membranes. On the back of the head, the fontanel is completely healed by six months. The large wedge-shaped window on the top of the head can remain soft for up to 2 years.
The large fontanel helps doctors diagnose:
- The ultrasound of an ultrasound machine easily penetrates through a thin plate, which makes it possible to examine the state of the brain and individual structures, measure intracranial pressure, and identify pathological processes.
- In case of dehydration or high temperature, the fontanelle retracts or rises, allowing timely assistance to the child, identifying the symptoms of dangerous diseases, rickets, hydrocephalus.
The large fontanel in half of the children completely disappears by the age of one year. In other children, its ossification continues until one and a half to two years. Based on the size and condition of the natural cranial window, the doctor can guess how correctly the child is developing.
During monthly preventive examinations, the doctor must pay attention to the size of the fontanelle.
The size of the fontanelle after birth is influenced by several factors:
- Method of delivery. During caesarean section in children, ossification of the skull tissue occurs more slowly. Open areas may have an increased area.
- Date of birth. In premature babies, the side windows remain open for several months, which is not a deviation from the norm.
- Nutrition for the expectant mother. If there is a lack of vitamins in a pregnant woman's diet, the fetus may lack nutrients. The newborn has a disturbance in the structure of bone tissue and a slowdown in development. The problem practically does not arise when breastfeeding a baby.
- In 80% of cases, the rate of retraction of open fontanelles is influenced by heredity and congenital pathologies of the skeletal system.
During monthly preventive examinations, the doctor must pay attention to the size of the fontanel on the child’s head. Delayed overgrowth may indicate diseases that require urgent diagnosis and treatment.
Stages of fontanel overgrowth
After birth, the baby has 4 fontanelles. Two of them are on the sides and heal quickly if the baby is full-term. A small triangle-shaped fontanel on the back of the head closes by three months. The large fontanel on the crown measures approximately 2 x 2 cm. At 4 months it decreases to 1 x 1 cm. By 12-18 months it is completely closed.
Normally, the fontanel is flat, but sometimes it can swell or sink. Recession of the fontanelle can be caused by various reasons. This usually indicates a lack of fluid in the child’s body.
To understand whether the fontanel is normal, it is enough to undergo regular examinations by a specialist. He will either confirm or deny the presence of violations.
Reasons for incomplete closure
In premature babies, the membrane can remain soft for up to 2 years as a normal variant. The pediatrician checks the condition by palpation or recommends an ultrasound. There should be no pulsation of the veins, bulging or redness of the skin. If the fontanelle has not completely closed at 1 year of age, parents should not worry.
If the parietal fontanel is large, the doctor may suggest one of the following diseases:
- Rickets. With severe vitamin D deficiency, bone tissue changes structure, becoming softer and more elastic. It remains open for a long time and can be felt upon palpation. The baby becomes lethargic, sleeps a lot, sweats a lot during sleep and when moving. A characteristic feature is that a bald patch forms on the back of the head, closer to the neck, due to excessive hair loss.
- Congenital form of hypothyroidism. With pathologies and underdevelopment, the thyroid gland does not produce enough hormones, which are necessary for the full development of the bones of the skeleton and skull. Children have impaired digestion, suffer from chronic constipation, and often experience an umbilical hernia from straining. Young patients with this problem are often overweight.
- Hydrocephalus. Severe and life-threatening pathology occurs when a large amount of cerebrospinal fluid accumulates. An excess of fluid prevents the sutures from completely healing and disrupts the shape and structure of the head. The child's intracranial pressure increases, the circumference exceeds the norm for age. The disease is accompanied by convulsions, spasms, headaches, decreased hearing acuity and blindness.
- Achondrodysplasia. A rare pathological disease of bone tissue. The proportions of the body are disrupted, the limbs become shortened, and the sutures of the skull are weakly fused. The fontanel may not heal for up to 5 years.
- Chondrodysplasia. The problem is due to insufficient production of growth hormone. Bone tissue stops regenerating, bones practically do not grow. Children without proper and timely treatment become dwarfs.
The fontanel heals poorly in children with Down syndrome. Mutations are associated with impaired brain development and abnormal skull structure.
According to Dr. Komarovsky, if there are no symptoms of disease, additional diagnostics should not be carried out until 1.5 years.
What to do if the fontanel does not close?
If by the age of 18 months the baby’s fontanel is still closed, then you need to see a doctor. This may be normal for your child, or it may be a symptom of a pathological condition.
| Pathology | Impact on BR | Additional research | Your actions |
| Rickets | As a result of calcium deficiency, bones soften, including the bones of the skull. The BR is open for a long time, the edges of the bones are soft to the touch. Lethargy, sweating during sleep, and baldness of the back of the head appear. Bone growths form on the ribs and wrists. The legs are bent (see rickets in an infant) |
| Therapy with therapeutic doses of vitamin D |
| Achondrodysplasia | A bone disease that leads to impaired growth. The skeleton becomes disproportionate, the limbs are short, and the head is massive and wide. BR does not last long. |
| Prescribed growth hormone somatotopin |
| Congenital hypothyroidism | A lack of thyroid hormones, which also regulate bone growth, leads to prolonged failure of the fontanel to heal. In addition, the child has constipation, a nasal voice, and is sometimes combined with umbilical hernias. Children are lethargic, sleepy, and often large. |
| Thyroid hormone replacement treatment |
| Hydrocephalus | Increased cerebrospinal fluid pressure prevents the cranial bones from coming together. Along with the BR, which rises above the bones, the head circumference also increases. Additionally, the child may have seizures, developmental delays, and hearing and vision problems. |
| Treatment with anticonvulsants, diuretics, nootropics. Sometimes bypass surgery is performed. |
Open fontanel with rickets
Vitamin D in large quantities is necessary for building the skeleton. It forms bone tissue and combines with calcium and magnesium. The child receives it in large quantities with mother's milk and formula. It is produced by the body under the influence of sunlight.
With rare walks on the street, poor diet or diseases of the digestive tract, vitamin D is not produced or absorbed from foods. The problem often arises when living in the northern regions, artificial nutrition, or an incorrectly selected mixture. With a long-term decrease in the concentration of a beneficial microelement, rickets can develop and phosphorus ceases to be absorbed.
The disease changes the structure of the bone tissue of the child's skeleton and skull. It occurs between 3 months and 3 years of age. The posterior and parietal fontanel does not close for a long time; the growth and development of the chest may be impaired. The consequence of the pathology is:
- weakened immune system;
- frequent colds;
- change in body proportions;
- anemia;
- dilation of veins in the abdominal cavity;
- dental diseases;
- rachiocampsis.
If the fontanel is not completely overgrown at 2 years of age, the child experiences sweating, poor sleep, and growth retardation, the doctor may prescribe a number of diagnostic procedures.
Prevention of rickets in infants
In central regions, the disease is rare, but pediatricians remind us of the need for preventive measures. They must begin during a woman's pregnancy. You should walk in the fresh air every day, eat properly and nutritiously, and take a vitamin complex as recommended by your doctor.
After birth, the baby must be taken outside every day during the daytime. Breastfeeding is of great importance: mother's milk contains essential microelements for bone tissue.
In the absence of lactation, the mixture should be selected by a pediatrician, who may recommend additional vitamin D in liquid form. The drug must be prescribed to premature infants.
