Which fontanel is located at the back of the newborn skull and closes by 8 - 12 weeks?

Which fontanel is located at the back of the newborn skull and closes by 8 - 12 weeks?

• A. Anterior
• B. Posterior
• C. Sphenoidal
• D. Mastoid

Answer: (B)

The back of the newborn’s skull has the posterior fontanel, positioned where the sutures at the occipital-parietal region meet. It’s smaller and triangular and typically closes by about 8–12 weeks after birth. This early closure helps the skull become more rigid as the brain grows, while the front (anterior) fontanel remains open longer to accommodate rapid brain development, usually closing later in infancy. The other fontanels—on the sides near the temple area and behind the ear—have different locations and timelines, so they don’t match the description of a back-of-the-head fontanel that closes this early.

The back of the newborn’s skull has the posterior fontanel, positioned where the sutures at the occipital-parietal region meet. It’s smaller and triangular and typically closes by about 8–12 weeks after birth. This early closure helps the skull become more rigid as the brain grows, while the front (anterior) fontanel remains open longer to accommodate rapid brain development, usually closing later in infancy. The other fontanels—on the sides near the temple area and behind the ear—have different locations and timelines, so they don’t match the description of a back-of-the-head fontanel that closes this early.