part of corpus striatum nucleus lentiformis BTO:0002250 BrendaTissueOBO The part of the corpus striatum somewhat resembling a biconvex lens, divided into an external, larger, lateral part (putamen) and an internal, smaller, lighter colored medial part (globus pallidus), which is in turn subdivided into a smaller, medial, and a larger, lateral part by the medial medullary lamina. lenticular nucleus lentiform nucleus nucleus lenticularis