What are fontanelles in the fetal skull?

• A. Fontanelles are bone plates between skull bones in infants.
• B. Fontanelles are cartilaginous joints in the skull.
• C. Fontanelles are fibrous connective tissue gaps between skull bones in infants that allow growth of the brain.
• D. Fontanelles are air-filled cavities in infants skull.

Answer: (C)

Fontanelles are soft gaps between the skull bones in infants filled with fibrous connective tissue. This arrangement keeps the skull bones separate enough to allow rapid brain growth during infancy and to enable the head to mold as it moves through the birth canal. They are not solid bone plates, nor cartilaginous joints, nor air-filled cavities. Over the first years of life, these gaps gradually ossify as the skull bones fuse. The largest, the anterior fontanelle, typically closes by about 18–24 months, while the posterior one closes much earlier.