The lenticular shape that gives the lentiform nucleus its name is best appreciated in coronal sections, where putamen and globus pallidus together form a lens-shaped grey-matter mass interposed between the internal capsule medially and the external capsule and claustrum laterally. The horizontal striations of the corpus striatum, which inspired the name “striatum,” reflect alternating grey-matter bridges between caudate and putamen that cross the anterior limb of the internal capsule.

The Alexander-DeLong-Strick framework of parallel cortico-striato-thalamo-cortical loops, developed in the mid-1980s, divides basal-ganglia function into five segregated channels (motor, oculomotor, dorsolateral prefrontal, lateral orbitofrontal, anterior cingulate). The motor loop runs through the putamen and contributes to scaling, sequencing, and selection of movements. Other loops run through the caudate and ventral striatum and contribute to cognition, motivation, and oculomotor control.

The putamen is the site of the hypertensive haemorrhages familiar to emergency neurology: thin-walled lenticulostriate arteries off the middle cerebral artery rupture under sustained hypertension and produce characteristic deep bleeds. Imaging features (large lesion volume, mass effect, contralateral hemiparesis) and clinical course are well-stereotyped enough that the differential diagnosis is often clear at first imaging.