Definition
Definition
The fontanelle is a space located between the bones of the skull in newborns, and still possessing a membranous structure (that is to say, whose ossification is not yet complete).
Generalities
- In adults, the bones of the skull are almost completely fused, there remains only an almost virtual space at the junction between the different bony plates of the skull.
- In children this is not the case, because the growth of the brain not being finished, the bones of the skull are not yet fused.
Classification
We distinguish:
- La anterior fontanelle, also called the large fontanelle, is diamond-shaped and located between the frontal and parietal bones. It is more easily palpable, as it measures between two and three cm wide. It closes between the ages of one and a half and two and a half years.
- La posterior fontanelle, also called the small fontanelle, also has a triangular shape but is less wide (1/2 cm). It is located between the parietal bones and the occipital bone. It closes around 2 to 3 months.
Anatomy
The fontanelles are located on the middle part, at the top of the skull , and during the first two years of life, while ossification is not yet complete, they allow the growth of the brain which is particularly important during this period of life.
Symptoms
Pathophysiology
There are no specific fontanelle pathologies. However, various neurological diseases result in changes in the fontanelles:
- A Dehydration (loss of fluid in the newborn or infant), causes depression of the anterior fontanelle (fontanelle hollowing under the finger)
- The hydrocephalus, or a meningitis can be translated by a intracranial hypertension (increased tension inside the skull) sometimes causing the fontanelle to protrude.
- If you have a rickets, the anterior fontanelle is somewhat slow to close and therefore appears excessively wide
- La craniosynostosis, which corresponds to premature fusion of the bones of the skull, results in a smaller than normal volume of the skull.
Medical exam
Physical examination
In newborns, during the neurological examination, palpation of the fontanelles is of great importance. They should not be bulging or sunken.