An infant has premature closure of the suture between the frontal and parietal bones. This suture is which one?

The suture between the frontal and parietal bones is known as the coronal suture. This fibrous joint runs across the top of the skull and is significant in separating the frontal bone from the two parietal bones.

Premature closure of the coronal suture can lead to specific types of craniosynostosis, which can affect the shape of the head and potentially lead to increased intracranial pressure or developmental issues. Understanding the location and function of the coronal suture is crucial in the context of pediatric health and cranial development, as it plays a critical role in the growth and shape of the skull during infancy and early childhood.

The other sutures listed do not relate to the frontal and parietal bones in this context. The frontonasal suture connects the frontal bone with the nasal bones, the lambdoid suture is located at the back of the skull connecting the parietal bones with the occipital bone, and the sagittal suture runs between the two parietal bones down the midline of the skull. Thus, recognizing the coronal suture's specific role helps clarify why this choice is the correct answer.