a large fiber bundle emerging from the anterior part of the thalamus in the anterior and rostal direction, in part joining the medial fibers of the internal capsule, and in part curving laterally around the medial margin of the capsule into the innominate substance. Many of its fibers establish a reciprocal connection of the mediodorsal nucleus of the thalamus with the orbital gyri of the frontal lobe, but numerous other fibers constitute a conduction system from the amygdala and olfactory cortex to the mediodorsal nucleus.ansa peduncularis. SYN: inferior thalamic radiation [TA], radiatio inferior thalami [TA], pedunculus thalami inferior.