Another area connected through the extreme capsule is the ventral region of the insula.

Its connections through the extreme capsule link it to the auditory and multisensory areas of the superior temporal sulcus.

The claustrum is a fraction of a millimetre to a few millimetres deep, and is a vertical curved sheet of sub cortical gray matter oriented sagittally between the white matter tracts of the external capsule and extreme capsule.

The extreme capsule is a long association fiber pathway of white matter in the brain that provides bidirectional communication between such areas as the claustrum and the insular cortex, and the inferior frontal gyrus (Broca's area) and the middle-posterior portion of the superior temporal gyrus(Wernicke's area).