The external capsule contains white matter tracts situated between the putamen and claustrum. It is separated from the internal capsule via the putamen (but eventually joins the internal capsule around the lentiform nucleus) and extreme capsule via the claustrum. It is made of claustrocortical fibers dorsally and the uncinate fasciculus and inferior frontal occipital fasciculus ventrally. Functionally, the white matter of the external capsule contains fibers known as corticocortical association fibers that connect the cerebral cortex to other cortical areas. It also contains cholinergic fibers from the basal forebrain to the cerebral cortex.