abnormal diencephalon morphology abnormal subthalamus morphology MP:0000834 MPheno.ontology abnormal ventral thalamus any structural anomaly of the anterior part of the diencephalon that lies between the thalamus, hypothalamus, and tegmentum of the mesencephalon, including subthalamic nucleus, zona incerta, the fields of Forel, and the nucleus of ansa lenticularis subthalamus dysplasia ventral thalamus dysplasia