A, Left hemisphere. The coronal, sagittal, lambdoid, and squamosal sutures have been pre-served. The anterior and posterior meningeal branches of the middle meningeal artery course along the dura. The pterion is located at the lateral margin of the sphenoid ridge near the junction of the coronal, squamosal, and frontosphenoid sutures. B, The dura has been removed while preserving the sutures. The coronal suture crosses the posterior part of the superior, middle, and inferior frontal gyri in front of the precentral sulcus. The central sulcus has a more posterior slope than the coronal suture, thus placing the coronal suture nearer the lower end of the central sulcus than the upper end. The anterior part of the superior temporal line overlies the inferior frontal sulcus, extends posteriorly near the junction of the middle and lower thirds of the pre- and postcentral gyri, and turns downward, crossing the supramarginal and angular gyri and the posterior temporal lobe. The squamosal suture is situated just below the anterior part of the sylvian fissure and posteriorly turns down-ward to cross the midportion of the temporal lobe. C, The sutures have been removed to expose the gyri and sulci. The lower end of the precentral gyrus is located behind the pars opercularis and the postcentral gyrus is located in front of the supramarginal gyrus. D, Right side before removal of the sutures. The relationships are similar to those on the left side, except that the anterior part of the squamosal suture courses at the level of the anterior part of the sylvian fissure, rather than being positioned below the sylvian fissure as shown in B. The coronal suture has less slope from below to above than the central sulcus, thus placing the lower end of the central sulcus nearer the coronal suture than the upper end. In D there are relatively well-developed superior, middle, and inferior temporal gyri, but in C the temporal lobe is divided into a superior temporal gyrus, but there is no clear demarcation between the region of the middle and inferior temporal gyri that are broken into multiple segments by the oblique sulci. There is a gyral bridge (yellow arrow) below the central sulcus between the lower end of the pre- and postcentral gyri on both sides so that neither central sulcus reaches the sylvian fissure. The supramarginal gyrus wraps around the upturned posterior end of the superior temporal sulcus. E, Another right hemisphere. Green pinheads have been placed along the site of the coronal, squamosal, and lambdoid sutures. The pterion is located at the junction of the squamosal and coronal sutures at the lateral end of the sphenoid ridge and stem of the sylvian fissure. A yellow pin (yellow arrow) has been placed along the edge of the superior sagittal sinus at the 50% point along the nasion-to-inion line. Another red pin (red arrow) has been placed 2 cm behind the 50% point, which is usually located at the upper end of the central sulcus. The central sulcus is usually placed 3.5 to 4.5 cm behind the coronal suture. (Images courtesy of AL Rhoton, Jr.)