Answer:
The anterior fontanelle usually closes between 12-18 months of age, while the posterior fontanelle closes by around 2–3 months old.
Step-by-step explanation:
The soft spot on a baby, also known as the fontanelle, is an anatomical feature that refers to the areas of the infant's skull where the cranial bones have not yet completely fused together. There are two fontanelles in a newborn's skull: the anterior fontanelle located at the top front portion of the head and the posterior fontanelle found at the back.
The anterior fontanelle is typically larger and diamond-shaped, while the posterior fontanelle is smaller and triangular. These fontanelles allow for the growing brain and skull to accommodate each other during childbirth and early infancy.
The process of ossification, which involves the gradual fusion of these cranial bones, begins shortly after birth and continues over time. The anterior fontanelle usually closes between 12-18 months of age, while the posterior fontanelle closes by around 2–3 months old.