Final answer:
The parietal ridge begins at the sides of the skull along the temporal lines of the parietal bones, beneath the parietal bone of the cranium. It is directly above the point where temporal lines curve downward.
Step-by-step explanation:
The parietal ridge begins where the temporal lines of the parietal bones start to curve downward and are located at the sides of the skull. These temporal lines mark the point of attachment for the temporalis muscle, an important muscle involved in chewing. Each parietal bone forms a significant portion of the upper lateral side of the skull and defines part of the cranial structure, bounded anteriorly by the frontal bone, inferiorly by the temporal bone, and posteriorly by the occipital bone. The parietal ridge can be identified by feeling the prominent lateral line that travels upwards from the ear towards the crown of the head, which is directly beneath the parietal bone of the cranium.