What is the shape of the anterior fontanelle?

Appeared in: RRB Nsg. Superintendent-20 July 2019 (Shift-3rd)

Explanation

The anterior fontanelle is a diamond-shaped soft spot on a baby's skull.
It is located at the junction of the sagittal, coronal, and frontal sutures.
This shape is formed by the meeting of the two frontal and two parietal bones.
It is the largest fontanelle and typically closes between 18 to 24 months after birth.

Option A: The anterior fontanelle is not square-shaped. This is an incorrect anatomical description.
Option B: The anterior fontanelle is not rectangular. This is an incorrect anatomical description.
Option D: A triangular shape describes the posterior fontanelle, not the anterior one.

Visual 1: Diagram - A superior (top-down) view of a neonatal skull, clearly labeling the diamond-shaped anterior fontanelle, the triangular posterior fontanelle, and the intersecting sutures (sagittal, coronal, frontal, lambdoid). This helps visualize the shapes and locations.
Visual 2: Illustration - An infant's head showing a nurse gently palpating the anterior fontanelle. Captions could explain what a normal, sunken, or bulging fontanelle feels like and what each indicates.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy of the neonatal skull, specifically the fontanelles as background academic context rather than a clinical decision trigger.
Nurses routinely assess fontanelles during newborn and infant check-ups as a key indicator of hydration status and neurological health.
A sunken fontanelle is a critical sign of dehydration, prompting the nurse to assess for other signs like poor skin turgor, dry mucous membranes, and decreased urine output, and to initiate rehydration measures.
A tense or bulging fontanelle at rest is a red flag for increased intracranial pressure (ICP), which could be due to meningitis, hydrocephalus, or head trauma. This requires immediate medical evaluation.

How to Approach the Question

This is a factual recall question from anatomy.
Identify the key term in the question: 'anterior fontanelle'.
Recall the anatomical features of the neonatal skull.
Specifically, remember the shapes of the two main fontanelles: the anterior and the posterior.
The anterior fontanelle is diamond-shaped, while the posterior is triangular.
Select the option that correctly matches the shape of the anterior fontanelle.

Concept Tested & Keywords

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Practise the full RRB Nsg. Superintendent-20 July 2019 (Shift-3rd)

Attempt every question from this paper in a timed mock, then review the full solution for each one.