Question:easy
Which of the following fontanelles is the last to close?
Which of the following fontanelles is the last to close?
Show Hint
Posterior closes first; the large diamond-shaped anterior fontanelle is the last, by 18-24 months.
Updated On: Jun 23, 2026
- Anterolateral
- Anterior
- Lateral
- Occipital
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: List the four pairs and the midline gaps with their approximate closure times, since the question is purely about timing. Posterior closes first, around 2-3 months.
Step 2: Working through the timeline: the sphenoidal (anterolateral) follows near 6 months, then the mastoid (posterolateral) from 6 to 18 months.
Step 3: The anterior fontanelle, the largest and most clinically useful for assessing hydration and intracranial pressure, persists the longest and closes around 18 to 24 months of age.
Step 4: Therefore, among the choices given, the anterior fontanelle is the final one to ossify; the anterolateral and lateral (mastoid) ones close well before it.
\[\boxed{\text{Anterior}}\]
Step 2: Working through the timeline: the sphenoidal (anterolateral) follows near 6 months, then the mastoid (posterolateral) from 6 to 18 months.
Step 3: The anterior fontanelle, the largest and most clinically useful for assessing hydration and intracranial pressure, persists the longest and closes around 18 to 24 months of age.
Step 4: Therefore, among the choices given, the anterior fontanelle is the final one to ossify; the anterolateral and lateral (mastoid) ones close well before it.
\[\boxed{\text{Anterior}}\]
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