Skull & Cranial Anatomy
Posterior fontanelle
The posterior fontanelle is the smaller soft spot toward the back of a baby's head, usually closing within the first few months.
In short: Posterior fontanelle
- It is smaller than the anterior fontanelle.
- It closes earlier, typically within months.
- It is part of the newborn skull's growth design.
- It reflects the flexibility a baby's skull needs to grow.
What it is
It is the back soft spot on a baby's head, smaller than the anterior fontanelle and closing earlier, typically within the first few months.
Understanding Posterior fontanelle
Like the anterior fontanelle, it reflects the flexibility a baby's skull needs to grow, and it closes as the bones come together. Because it is smaller and closes sooner, it plays a lesser role in monitoring than the anterior fontanelle, though both are part of the newborn skull's normal design.
Why it matters
Understanding the posterior fontanelle helps families recognize it as a normal newborn feature and distinguish normal soft spots from the abnormal opening of an encephalocele.
Common questions
When does it close?
Usually within the first few months.
Is it smaller?
Yes, smaller than the anterior fontanelle.
Is it normal?
Yes — it is a normal newborn feature.
Bottom line
The posterior fontanelle is the smaller back soft spot, closing within the first few months.
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