Understanding Fontanelles: The Infant's Soft Spots
For infants, the presence of soft spots, known as fontanelles, is a natural and expected part of development. These are spaces between the skull bones that have not yet fused together. They allow the baby’s head to pass through the birth canal and provide room for the brain to grow rapidly. While there are six fontanelles at birth, two are the most prominent.
The Major Infant Fontanelles
- Anterior Fontanelle: This is the most well-known soft spot, located on the top of the head, where the frontal and parietal bones meet. It is typically diamond-shaped and the largest of the soft spots. You should be able to feel it as a flat, firm area covered by a thick fibrous membrane. In a healthy infant, it may have a slight inward curve and can sometimes visibly pulsate, which is the result of blood pumping through the body. This fontanelle normally closes between 9 and 18 months of age.
- Posterior Fontanelle: Situated at the back of the head, this fontanelle is smaller and triangular. It usually closes much sooner than the anterior fontanelle, often by age 2 to 3 months.
How to Examine an Infant's Soft Spot
To check your baby's fontanelles, follow these steps:
- Wait until the baby is calm: The fontanelle can temporarily bulge when the baby is crying, coughing, or vomiting. A calm, upright position will give you the most accurate reading.
- Use gentle pressure: With a clean hand, lightly touch the top of your baby's head. The fontanelle should feel firm and flat or slightly sunken.
- Observe for changes: Notice if it appears bulging when the baby is calm, or if it is significantly sunken. Any noticeable difference should be discussed with a pediatrician.
Concerning Soft Spots in Adults
Unlike infants, adults have completely fused skull bones. Therefore, the presence of a new or persistent soft spot in an adult is considered an abnormal finding and should be evaluated by a healthcare professional. The cause is often related to an underlying medical condition, injury, or past surgical procedure. It is crucial not to ignore a soft spot on an adult's head, as it can indicate a serious health issue.
Potential Causes for an Adult Soft Spot
- Trauma: A previous head injury, even one that seemed minor at the time, could have resulted in a bone depression or damage that heals imperfectly, creating a soft or indented area.
- Genetic or Congenital Conditions: Some people may have genetic disorders that affect bone development, such as craniosynostosis or cleidocranial dysplasia, which can cause incomplete skull closure that persists into adulthood.
- Medical Conditions: Conditions that affect fluid or pressure within the skull, such as hydrocephalus, can cause a re-opening of a soft spot or prevent it from closing fully.
- Post-Surgical Complications: If a person has undergone neurosurgery involving the skull, complications during the healing process could lead to a persistent soft spot.
How to Address a Soft Spot on an Adult's Head
If you find an unusual soft spot on your head, the correct action is to seek a medical professional's opinion. A doctor will perform a physical exam and may order diagnostic tests like a CT scan or MRI to determine the cause. Self-diagnosis or manipulation of the area is not recommended.
Infant vs. Adult Soft Spot: A Comparison
| Feature | Infant Soft Spot (Fontanelle) | Adult Soft Spot |
|---|---|---|
| Purpose | Accommodates brain growth and facilitates passage through the birth canal | No normal purpose; indicative of an underlying issue |
| Normalcy | Expected, normal, and closes over time | Abnormal and warrants medical evaluation |
| Location | Specific, predictable anatomical sites | Varies; could be anywhere on the skull |
| Feel | Firm, fibrous membrane; may pulsate | Can be tender, swollen, bulging, or indented |
| Health Implication | Bulging or sunken appearance can signal issues like dehydration or increased pressure | Can be caused by genetic conditions, trauma, or disease, potentially carrying serious risks |
When to Seek Medical Attention
Any uncertainty regarding a soft spot should prompt a consultation with a healthcare provider. Prompt attention is critical, especially for adults. For infants, while the fontanelle is normally protected, a significantly bulging or sunken appearance that persists when the baby is calm and upright is a signal for concern. This could be accompanied by other symptoms, such as irritability, fever, or poor feeding. In adults, any new or growing soft spot, especially if it is tender or accompanied by headaches, neurological changes, or other symptoms, requires immediate medical evaluation. Early diagnosis is key to addressing any underlying issues.
For more information on the anatomy and development of soft spots, you can consult reliable sources such as the Health Library at NewYork-Presbyterian [https://www.nyp.org/healthlibrary/definitions/soft-spots-fontanelles].
