Fig. 21C.Overview of the major afferent pathways to the hypothalamus. (C) Course of afferent fibers from the thalamus, subthalamus and zona incerta to the hypothalamus. Efferents from the hypothalamus coursing in the mammillo-subthalamic tract are also shown. On the right side of the image, a three-dimensional reconstruction shows the anatomical structures schematically depicted on the left side. aap = amygdalofugal and amygdalopetal components of the ansa peduncolaris; ac = anterior commissure; Ah = Ammon horn; al = ansa lenticularis; am = amygdala; ap = ansa peduncularis; ATn = anterior thalamic nucleus; cc = corpus callosum. CN = caudate nucleus; CS = corpus striatum; df = dentate fascia; fl = fasciculus lenticularis; fr = fasciculus retroflexus; ft = fasciculus thalamicus; fx = fornix; H1 = field H1 of Forel; H2 = field H2 of Forel; ha = habenula; hipp = hippocampus; HYP = hypothalamus; ic = internal capsule; iTp-ap = inferior thalamic peduncle of the ansa peduncularis; LTn = lateral thalamic nucleus; mb = mammillary body; MFB = medial forebrain bundle; mst = mammillo-subthalamic tract; MTn = medial thalamic nucleus; mtt = mammillo-thalamic tract; olf-a = olfactory area; olf-n = olfactory nerve; olf =olfactory tubercle; opt = optic tract; pir = piriform cortex; pvs = periventricular system; RF = reticular formation of the brainstem; sa = septal areas; SN = substantia nigra; Sub = subthalamus; zi = zona incerta; III = third ventricle. (From Toni R, Malaguti A, Benfenati F, Martini L: The human hypothalamus: a morphofunctional perspective. J Endocrinol Invest 27 (supp to n.6), 73-94, 2004.)