Fontanelles

Fontanelles are soft spots on a baby's head which, during birth, enable the soft bony plates of the skull to flex, allowing the child's head to pass through the birth canal. The sutures or anatomical lines where the bony plates of the skull join together can be easily felt in the newborn infant. The fontanelles are the membranous gaps between the cranial bones that make up each suture.

Anatomy of Fontanelles

There are two primary fontanelles: the larger anterior fontanelle and the smaller posterior fontanelle. The anterior fontanelle is located at the junction of the frontal and parietal bones; it is a lozenge-shaped gap that may remain open until the child is around two years old. The posterior fontanelle is located between the parietal and occipital bones; it is generally triangular in shape and closes by the end of the first year of life.

Clinical Significance of Fontanelles

The fontanelles allow for rapid stretching and deformation of the neurocranium as the brain expands faster than the surrounding bone can grow. Premature closure of the sutures, known as craniosynostosis, can cause a misshapen skull.

The tension of the fontanelles can also be used to assess the pressure within the skull. Bulging fontanelles may be a sign of increased intracranial pressure, while sunken fontanelles may be a sign of dehydration or malnutrition.

Examination of Fontanelles

During a medical examination, the fontanelles are assessed for size, tension, and whether they are bulging or sunken. This can provide important information about the child's health. For example, a bulging fontanelle can be a sign of hydrocephalus (a buildup of fluid in the brain), meningitis (inflammation of the membranes surrounding the brain and spinal cord), or a brain tumor.

See Also

• Cranial sutures
• Craniosynostosis
• Hydrocephalus
• Meningitis

References

Fontanelles Resources
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