Fontanelle or fontanel

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Normal full term baby has 6 fontanelle :

• Anterior
• Posterior
• 2 Mastoid
• 2 Sphenoidal

Posterior :

• Close at birth
• In only 3% it is open (here it just admits tip of finger)

Anterior : 

• Diamond shape
• Open at birth
• 2.5 x 2.5 cm
• Pulsatile
• Closes at 18 - 24 months life.

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Causes of Delayed closure of Anterior fontanelle :

1. Down's Syndrome
2. Hypothyroidism
3. Hypophosphatasia
4. Rickets
5. Cleidocranial dysostosis

First four (1-4) and idiopathic are causes of delayed dentition. (Delayed dentition is non eruption of teeth by 13 months life )

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Early closure of Anterior fontanelle : Craniosynostosis
Complications :

• Microcephaly
• Increased ICT - Optic atrophy
• Cosmetic - head shape (if only one suture fuses early)

Associated syndromes :

• APERT (AD)
• CROUZON (AD)
• CARPENTER - Autosomal recessive
• PFIFFER (AD)

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Increased ICT : Anterior fontanelle - bulging & non pulsatile
Dehydration : Depressed Anterior fontanelle

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Img source : http://en.wikipedia.org/wiki/File:Gray197.png