The Parietals are paired left and right. Externally, each possess a Superior, and Inferior Temporal Line, to which the temporal muscle is attached. The lines run from the Frontal Crest of the anterior frontal bone to the Supra-Mastoid Crest on the posterior portion of the temporal bone. The parietals articulate with each other by way of the Mid-Sagittal Suture, and with the frontal bone anteriorly by way of the Coronal Suture. These two sutures generally form a right angle with one another. Posteriorly, the parietals articulate with the Occipital Bone by way of the Lambdoid Suture. The intersection of the Lambdoid and Sagittal Sutures approximate a 120 degree angle on each of the parietals and the occipital bone. Among the sutures the Lambdoid is by far more serrated than either the Sagittal or the Coronal. Inferiorly the Parietal articulates with the temporal bone by way of the Squamosal and Parieto-Mastoid Sutures. On the external surface near the center of the bone is the Parietal Eminence. Slightly posterior to the eminence there may be a Parietal Foramen.