What shape is the posterior fontanelle?

The posterior fontanelle is commonly described as triangular in shape. It is located at the junction of the parietal and occipital bones of an infant's skull. The triangular shape is important for clinical assessments, particularly during a newborn's examination.

This shape allows for easy palpation and helps healthcare providers assess the baby's hydration status, intracranial pressure, and development. The posterior fontanelle typically closes within the first few months of life, and understanding its shape aids in recognizing normal versus abnormal findings during physical examinations.

In contrast, the other shapes mentioned do not accurately represent the posterior fontanelle's form, which is distinctly characterized by its triangular configuration.