Location of human pyramidal tract in the internal capsule: anatomic evidence.

A patient with a small infarct located posteriorly in the internal capsule had 9 years of weakness of the contralateral face, arm, and leg. At necropsy, it was found that degeneration of the corticospinal tract was almost complete in the midbrain and medullary pyramid. This case supports the increasing evidence that the human pyramidal tract is located in the third quarter of the posterior limb of the internal capsule.