Infant cranial fontanelles and anatomy
Surely you have heard of the cranial fontanelles of the newborn with reference to the soft, pulsating parts in the baby's head.
But what are they and what are they used for? You will find the answer to these and other questions in the following article.
The infant's skull
The skull is the body structure composed of the set of bones that form the head of the human skeleton.
The skull protects the noble structures of the head such as the brain, cerebellum, brainstem and other sensory organs and offers them space indispensable for operation.
Just think of the eye cavities that house the eyeballs, the mouth cwhich houses the tongue, or to the cranial facial structures that house the nasal cavities.
Cranial bones
The bones that make up the human skull are 22, joined together by means of cranial sutures.
Of these 22 bones, some are even and symmetrical.
This means that if we ideally divide the head into two halves on a sagittal plane, we find them identical and in the same position on the left and right.
The infant's skullIn addition to bones and sutures, it also has the cranial fontanelles.
Le functionality of fontanelles and cranial sutures are essential to enable a optimal cranial growth.
How the infant's skull is formed
The skull is made up of several bones joined together, both morphologically and embryologically; for this reason it can be divided into splanchnocranium and neurocranium.
Lo splanchnocranium makes up the facial massif, i.e. the front part of the head.
It is also called viscera-cranium because it provides indispensable space to the functioning of main sense organs such as the mouth, nose and eyes.
The Neurocranium is that region of the skeleton of the head that forms a cavity containing the main organs of the central nervous systemnamely the brain, cerebellum and brainstem.
In total, there are 22 cranial bones.
From a functional point of view, the skull
The splanchnocranium consists of 14 bones [Palatine bones (2), Nasal bones (2), Zygomatic bones (2), Lacrimal bones (2), Vomeres (1), Mandible (1), Maxillary bones (2), Inferior nasal conchae (2)] .
The neurocranium consists of 8 bones [occipital bone (1), frontal bone (1), temporal bone (2), parietal bone (2), sphenoid bone (1), ethmoid bone (1)] .
Cranial sutures of the newborn
Le cranial sutures are the skull joints that maintain continuity between one bone and the next.
Sutures are also defined as junction lines and are formed by dense fibrillar connective tissue.
Main cranial sutures
The skull is composed of 22 cranial bones.
Cranial sutures are even more so.
Below we list the main cranial suturesespecially those that might be affected in the craniostenosis of the newborn.
- Metopic suture
- Coronal suture
- Sagittal suture
- lambdoid suture
1.Metopic suture
The metopic suture is centrally joins the two frontal bones and extends from the nose to the anterior fontanelle.
This is why it is also called a frontal suture.
The metopic suture merges in childhoodusually within the first 5-6 years of life.
If the metopic suture is ossified from birth or ossifies in the very first months of life, the trigonocephaly.
2. Coronal suture:
There are two coronal sutures, one on the right and one on the left.
The coronal suture is formed between the frontal bone and the parietal bone.
3. Sagittal suture:
The sagittal suture is located on the midline of the skull and t is formedbetween the two parietal bones.
It extends from the anterior fontanelle to the posterior fontanelle.
4. Lambdoid suture:
The lambdoid suture is two, even and symmetrical.
They form between the occipital bone and the parietal bone.
Cranial fountains of the infant's head
Cranial fontanelles are those soft and membranous spacesyes they are created where at least two sutures intersect cranial bones (or at least three cranial bones).
They owe their name 'fontanelle' to the fact that they can occasionally be seen pulsating like a fountain.
Especially the front central fontanelle is easy to palpate because it may be swollen or dimpled, soft and large on palpation with a finger.
The cranial fontanelles are delicate and soft to the touch because they are formed by a fibro-cartilaginous tissue which makes them much softer than a bone structure.
At least 2 cranial fontanelles are usually known, the one front centre and that rear centre.
Not everyone knows the other 4 lateral cranial fontanelseven and symmetrical.
We find two on the right and two on the left.
We have the front side fontanelle, which is called pterion or sphenoidal fountain.
We have the rear side fountain, which is called asterion or mastoid fountain.
Central anterior cranial fontanel of the newborn (Bregma)
The front fountain is called Bregma and has the form of a lozengeof a diamond.
It is the easier to palpate for both parents and health professionals.
This fontanelle is formed at the point where the two parietal bones and the anterior frontal bones converge. In the anterior cranial fontanel converge the right and left coronal sutures (cranial sutures between the frontal and parietal bones) and the sagittal suture (median cranial suture formed between the two parietal bones).
The anterior fontanelle is the most easily palpable because it is the largest of the 6 cranial fontanelles with a length ranging from 1 to 3 cm.
In healthy subjects, Bregma ossifies around the 18th month of life and, certainly, by the time the child is two years old.
According to statistics, the front fountain is closed
- In a small 1% of infants in the third month of life,
- In 38% of children at 12 months of age and
- In 96% of children in the 24th month of life.
Central posterior cranial fontanel of the newborn (Lambda)
The rear fountain is the second best-known fountain and has a shape of triangle.
LambdaThis is also the name of the rear fountain, located near the rear apex of the cranial vault, a little further back.
More precisely, it is formed at the point where the sagittal suture (the suture that is centrally between the two parietal bones) and the lambdoid suture (the suture between the parietal bone and the occiput) intersect.
The posterior fontanelle is part of the cranial vault and its size is around approx. 0.5 cm.
The ossification period, i.e. closure of the cranial fontanelle, is around 2-3 months of the infant's life.
Anterolateral cranial fontanel of the newborn (Sphenoidal)
The antero-lateral fontanelle is called sphenoidal fountain (named after the sphenoid bone).
The sphenoid fontanelle is even and symmetrical (i.e. it is present, in the same position, in both the right and left halves of the skull in a symmetrical manner).
As its name suggests, it is positioned between the sphenoid bone, the parietal bone, the temporal bone and the frontal bone.
The ossification period, i.e. the period within which the sphenoid fontanelle closes, is around 6 months of the child's life (in healthy children).
Postero-lateral cranial fontanel of the newborn (Mastoidea)
The postero-lateral fontanelle is also called mastoid fountain, a name derived from the mastoid part of the temporal bone.
The mastoid fontanelle, like the sphenoid fontanelle, is even and symmetrical; it is found on both the right and left.
It is located just behind the ear between the temporal bone, occipital bone and parietal bone.
The mastoid fountain ossificatherefore closes from 6 to 18 months of the child's life.
Ossification and closure of the infant's cranial fontanelles
To recapitulate, the process of ossification of the fontanelles occurs gradually from the first months until around the second year of life.
To be more precise, the infant's 6 cranial fontanelles close:
- Around II-III months of life, for the posterior fontanelle;
- Around the 18th month of life, for the anterior fontanelle;
- Around the sixth month of life, for the sphenoid fontanelle;
- Between the 6th and 18th month of life, the mastoid fontanelle.
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