The anterior fontanel closes in an infant at the age of?

Appeared in: DSSSB -28 August 2019 (Shift-2)

Explanation

The anterior fontanel is the larger, diamond-shaped 'soft spot' on an infant's skull.
Its primary function is to allow for the rapid growth of the brain that occurs during the first year of life.
Normal closure of the anterior fontanel occurs between 12 and 18 months of age.
This timeframe is a key developmental milestone that nurses assess to monitor normal growth.

Option B: This range is significantly delayed for anterior fontanel closure and would be considered abnormal, warranting investigation for underlying conditions like hypothyroidism or hydrocephalus.
Option C: This range is also outside the typical upper limit for closure. While some variability exists, closure this late is considered delayed and requires further assessment.
Option D: This timeframe is incorrect for the anterior fontanel. It more closely aligns with the closure of the much smaller, triangular-shaped posterior fontanel, which typically closes by 6-8 weeks (around 2 months).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Infant developmental milestones: Anterior fontanel closure as background academic context rather than a clinical decision trigger.
Assessing fontanels is a fundamental part of the neonatal and infant physical examination for nurses. It provides a non-invasive window into the infant's neurological status and hydration level.
A bulging fontanel in a resting, calm infant is a red flag for increased intracranial pressure (ICP) and requires immediate medical attention.
A sunken or depressed fontanel is a key clinical sign of moderate to severe dehydration in an infant.

How to Approach the Question

First, identify the key anatomical structure in the question: the 'anterior fontanel'.
Second, recognize that the question is asking for a specific developmental timeframe, which is a factual recall question.
Third, differentiate the anterior fontanel from the posterior fontanel. Recall that the anterior is larger and closes much later.
Fourth, access your knowledge of infant developmental milestones. The anterior fontanel allows for significant brain growth in the first year.
Finally, compare the recalled timeframe (12-18 months) with the given options and select the one that matches.

Concept Tested & Keywords

Concept Tested: Infant developmental milestones: Anterior fontanel closure
Stem keywords: anterior fontanel, closes, infant, age
Lead-in keywords: at the age of
Clinical cues: Age/sex group narrows the expected diagnosis, intervention, or normal reference range.
Negative lead-in flag: false

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E6 Comprehensive Textbook of Community Health NursingShyamala D part 1 (pp 26-389 of 389) p. 300-302

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 1357-1359

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