E, Superolateral view at the foramen of Monro showing the genu of the capsule reaching the ventricular surface lateral to the foramen of Monro. F, Superolateral view of the section at the level of the anterior commissure. At this level below the frontal horn and anterior limb of the internal capsule, and above the anterior perforated substance, the putamen, lentiform nucleus, globus pallidus, and caudate head blend into a large mass of gray matter. The posterior limb of the internal capsule, located between the lentiform nucleus and the thalamus, is still present in the cross section even though the anterior limb is absent. In coronal cross sections, the lentiform nucleus is typically lens-shaped, but in the axial cuts, as shown here, the lentiform nucleus, composed of the putamen and globus pallidus, has a tear-drop shape with a broad, rounded head anteriorly and a pointed tail posteriorly. The amygdala and head of the hippocampus, separated by the uncal recess, are exposed below the lentiform nucleus. G, Superolateral view of a cross section extending below the frontal horn and through the red and subthalamic nuclei and upper part of the cerebral peduncle. At this level, just above the anterior perforated substance, the lentiform and caudate nuclei blend into the nucleus basalis and accumbens to create a large collection of gray matter. The red nucleus is located in the center of the midbrain. The right subthalamic nucleus is a lens-shaped nucleus situated in the interval between the cerebral peduncle and the midbrain. H, The part of the basal surface of the frontal lobe above the sylvian fissure has been removed to expose the upper edge of the cerebral peduncles and the red and subthalamic nuclei located just behind the peduncle. The optic tract passes laterally around the upper margin of the cerebellar peduncle. The left half of the brainstem has been sectioned obliquely to expose the substantia nigra located just below the subthalamic nucleus. (Images courtesy of AL Rhoton, Jr.)