Final answer:
The parietal bones are surrounded by the coronal, sagittal, lambdoid, and squamous sutures, which connect the parietal bones to adjacent skull bones, providing strength and protection for the brain.
Step-by-step explanation:
The sutures surrounding the parietal bones are the coronal suture, the sagittal suture, the lambdoid suture, and the squamous suture. The coronal suture joins the parietal bones to the frontal bone, running from side to side across the skull. The sagittal suture extends from the coronal suture along the midline at the top of the skull, uniting the right and left parietal bones. At the back of the skull, the sagittal suture meets the lambdoid suture, which connects the occipital bone to the parietal and temporal bones and is characterized by its lambda-like upside-down "V" shape. On the sides of the skull, the squamous suture joins the squamous portion of the temporal bone to the parietal bones.