Coronal section through the thalamus and subthalamus. Relationships among the lentiform nuclei, posterior limbs of the internal capsules and subthalamic nuclei are revealed. The lentiform nuclei, consisting of the putamen, globus pallidus externa and globus pallidus interna, are prominent wedge-shaped landmarks that lie just lateral to the internal capsule.  The paired thalami are located on either side of the midline third ventricle and medial to the posterior limb of the internal capsule. The subthalamic nucleus is a biconvex, lens-shaped nucleus that lies in the subthalamus medial to the posterior limb of the internal capsule and superior to the rostral pole of the substantia nigra of the midbrain. The hippocampal formation is visible in the ventromedial floor of the inferior/temporal horn of the lateral ventricle.  The lateral ventricles are abnormally dilated in this brain. (Image courtesy of AL Rhoton, Jr.)