internal capsule

This term is a specialized anatomical designation used primarily in neurology and neuroanatomy. It describes a specific structural arrangement of axons rather than a hollow capsule or a container, which can lead to confusion for non-specialists. The term emphasizes the "encapsulated" nature of the white matter fibers as they are squeezed between the thalamus and the basal ganglia.

In clinical contexts, the internal capsule is frequently discussed in relation to stroke or lesion sites, as its compact nature means that even a small area of damage can result in significant motor or sensory deficits across the opposite side of the body.