What is the normal duration for closure of the posterior fontanel in a newborn?

• A. 8 - 12 weeks
• B. 4 - 6 weeks
• C. 12 - 24 weeks
• D. 6 - 8 weeks

Answer: (A)

Fontanels are soft spots on a newborn’s skull that allow for brain growth and birth canal passage. The posterior fontanel, located at the back of the head, is small and closes earlier than the anterior one. The normal closure time is about 8 to 12 weeks after birth, roughly two to three months. This earlier closure happens because the bones at the back fuse sooner, while the anterior fontanel remains open longer to accommodate ongoing brain growth, usually closing around 12 to 18 months. Some variation exists, but 8–12 weeks is the commonly expected window for the posterior fontanel.