E, Lateral view of the hemisphere. In the next step, the sulci and gyri on the lateral surface are examined. The central sulcus ascends between the pre- and postcentral gyri. The precentral gyrus is located behind the pars opercularis. The postcentral gyrus is located in front of the anterior part of the supramarginal gyrus. To expose the ventricles for the dissection in the laboratory, an axial cut through the hemisphere is completed 1 cm above the posterior end of the long axis of the sylvian fissure (broken line). F, The same hemisphere after removal of the arteries and veins. The site of the cut (broken line) to expose the ventricles crosses the inferior frontal gyrus, the lower part of the central sulcus, and the supramarginal gyrus. G, Superior view into the lateral ventricles. The caudate nucleus forms the lateral wall and the septum pellucidum forms the medial wall of the frontal horn and body of the lateral ventricle. The rostrum of the corpus callosum forms the floor of the frontal horn. The thalamus is in the floor of the body of the lateral ventricle. The third ventricle is located below the body of the fornix. The choroid plexus is attached along the choroidal fissure located between the fornix and thalamus. H, The frontoparietal operculum has been removed to expose the insula lateral to the frontal horn and body of the lateral ventricle. Branches of the middle cerebral artery cross the insula and the plana temporale and polare. I, Superolateral view. The middle cerebral artery enters the operculoinsular compartment of the sylvian fissure by crossing the limen insula at the anteroinferior margin of the insula. The anterior part of the circular sulcus is separated from the frontal horn by the anterior isthmus of the central core of the hemisphere, and the posterior part of the circular sulcus is separated from the atrium by the posterior isthmus. J, Enlarged view of the middle cerebral branches coursing along the insula. The upper temporal surface is formed posteriorly by the planum temporale where the transverse temporal gyri are located and anteriorly by the planum polare, an area free of gyri, which contains a shallow trough along which the middle cerebral artery courses. The lower part of the circular sulcus is located medial to the planum polare and temporale above the roof of the temporal horn. (Images courtesy of AL Rhoton, Jr.)