Posterior Fontanelle Closure Delayed

What causes non closure of posterior fontanelle in an infant.

Posterior fontanelle closure delayed. It is the first to close. Closure of fontanelles and sutures delayed dentition horse riding stance thin limbs with prominent stiff joints coxa valga skeletal hypoplasia and dysplasia dystrophic ncbi nlm nih gov cranial fontanelles thin short clavicles dwarfism abnormally gracile ribs involving the posterior segments of the upper ribs slender long. The posterior fontanelle usually closes by the 8th week of life and the anterior fontanel closes by the 18th month of life on average.

This term applies if there is delay of closure of the fontanelles beyond the normal age. Delayed closure means persistence of open fontanel beyond 24 months of age. The closures eventually form the sutures of the neurocranium.

The sphenoidal and posterior fontanelles close during the first few months of life. In humans the sequence of fontanelle closure is as follows. The triangular posterior fontanel is located at the junction of the occipital and two parietal bones 1 5.

A list of the medical conditions associated with a large fontanel or delayed fontanel closure can be found in table 1 20 21 achondroplasia congenital hypothyroidism down syndrome rickets and. Other than the anterior and posterior fontanelles the mastoid fontanelle and the sphenoidal fontanelle are also significant. Prominent vascular markings of the bony calvarium are also common as is delayed closure of the anterior and posterior fontanelle which remained patent at a mean age of 7 4 years on a recent retrospective study of craniofacial findings ullrich et al 2012.

My almost 7 months old son s posterior soft spot is not closed he keeps getting dents whenever he sits in the car seat or high chair for too long and the dent becomes less visible the next day but still can be touched. The posterior fontanelle is on the upper rear part of the baby s head. This fontanelle is at the intersection of three different bones.

In humans the sequence of fontanelle closure is as follows. Most anterior fontanel close between 18 24 months of age. Large fontanel or delayed fontanel closure are discussed later in this article.