Posterior fontanelle

Anatomical feature in infants

Diagram of the fetal skull showing the posterior fontanelle

The posterior fontanelle is one of the two primary fontanelles in the human infant skull. It is a soft membranous gap (fontanelle) at the junction of the lambdoid and sagittal sutures. This anatomical feature is crucial during childbirth and early development.

Anatomy

The posterior fontanelle is located at the back of the skull, where the parietal bones meet the occipital bone. It is typically triangular in shape and smaller than the anterior fontanelle. The size of the posterior fontanelle can vary, but it is generally less than 1 cm in diameter at birth.

Function

The primary function of the posterior fontanelle, like other fontanelles, is to allow the infant's skull to be flexible during childbirth. This flexibility facilitates the passage of the head through the birth canal. Additionally, the fontanelles allow for rapid brain growth during the first year of life.

Closure

The posterior fontanelle usually closes earlier than the anterior fontanelle. It typically ossifies and closes by the time the infant is 2 to 3 months old. The closure of the fontanelle is a normal part of development and is an indicator of healthy growth.

Clinical Significance

The posterior fontanelle can be an important clinical indicator. A sunken fontanelle may indicate dehydration, while a bulging fontanelle can be a sign of increased intracranial pressure. Pediatricians often check the fontanelles during routine examinations to assess an infant's health.

Related Pages

• Anterior fontanelle
• Cranial sutures
• Infant skull
• Human skull