Anterior fontanelle

Last revised by Mohamed Saber on 11 Dec 2021

The anterior or frontal fontanelle is the diamond-shaped soft membranous gap (fontanelle) at the junction of the coronal and sagittal sutures. It persists until approximately 18-24 months after birth, after which it is known as the bregma. The precise timing of the anterior fontanelle closure is quite variable, and the research literature shows cases of closure from 6 months that may represent a normal variation in healthy babies 2 although early or late closure of a fontanelle is associated with various pathologies 3. The fontanelle normally measures between 0.6-3.6 cm (mean 2.1 cm) 3. The size of the anterior fontanelle tends to vary predictably with age, peaking around 2 months 2. It is the largest of the fontanelles and is the main sonographic window for performing cranial ultrasound.

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