Insular Region. Fiber dissection of the left cerebral hemisphere is shown. The long and short insular gyri, and the extreme capsule have been removed to expose the claustrum and external capsule. The claustrum has a dorsal part, composed of compact gray matter, and a ventral part, formed by islands of gray matter fragmented by fibers of the uncinate and inferior occipitofrontal fasciculi. The external capsule has a ventral part composed of the fibers of the uncinate and inferior occipitofrontal fasciculi exposed under the cortex of the limen insulae, and a dorsal part formed by claustrocortical fibers, which join the corona radiata. The superior longitudinal fasciculus courses above the external capsule and lateral to the corona radiata. The inferior longitudinal fasciculus is located medial to the temporal fibers of the superior longitudinal fasciculus. (Image courtesy of E de Oliveira)