At birth, the intersection of the coronal and sagittal sutures forms a diamond-shaped membrane-covered gap that normally ossifies by around 18 months of age. This landmark is the:
- A Posterior fontanelle at the lambda
- B Sphenoidal fontanelle at the pterion
- C Anterior fontanelle at the bregma ✓
- D Mastoid fontanelle at the asterion
Correct answer: C. Anterior fontanelle at the bregma
Explanation
The anterior fontanelle is the largest fontanelle, a diamond-shaped fibrous membrane at the bregma where the coronal and sagittal sutures meet. It closes between 12 and 18 months and remains clinically useful for assessing hydration and intracranial pressure and for ultrasound access. The posterior fontanelle at the lambda is triangular and closes by 2 to 3 months, while the sphenoidal and mastoid fontanelles are paired lateral fontanelles closing soon after birth.
Reference: Gray's Anatomy, 42nd ed.
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Written and medically reviewed by the StethoPrep medical team.