What is "internal capsule"

The internal capsule is a white matter structure situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the basal nuclei, separating the caudate nucleus and the thalamus from the putamen and the globus pallidus. The internal capsule contains both ascending and descending axons. The internal capsule contains fibres going to and coming from the cerebral cortex.

The corticospinal tract constitutes a large part of the internal capsule, carrying motor information from the primary motor cortex to the lower motor neurons in the spinal cord. Above the basal nuclei the corticospinal tract is a part of the corona radiata, below the basal nuclei the tract is called crus cerebri (a part of the cerebral peduncle) and below the pons it is referred to as the corticospinal tract.