Posterior fontanelle

Posterior fontanelle refers to a space between the bones of the skull where the occipital and the two parietal bones join together. The size of the fontanelle is typically between 0.5 and 0.7 centimeters. In most cases, the posterior fontanelle closes within approximately six to eight weeks after a baby is born. In the adult skull, the closure of this fontanelle signifies the meeting point of the sideways lambdoid suture and the midline sagittal suture. The merging point is called lambda. Occasionally, a delay in closure of the posterior fontanelle can indicate a connection to hydrocephalus or congenital hypothyroidism.

Fontanelles have a vital role in allowing skull to move and mold during labor. They also allow the brain to grow and develop after the baby is born.