The site of motor corticospinal fibres in the internal capsule of man. A computerised tomographic study of restricted lesions.

The distribution of the motor impairment was correlated to the site and extension of the lesion of 18 patients with restricted lesions of the internal capsule, detectable with computerised tomography (CT). In three cases the lesion was located in the anterior limb of the internal capsule and the patients did not suffer any motor defect. Among the 15 patients with lesions in the posterior limb, 13 presented a distribution of the motor weakness consistent with a location of the corticobulbar fibres in the genu and corticospinal fibres in the anterior half of the posterior limb. Our CT study confirms the classical view on the location of the pyramidal tract in the internal capsule of man, but also evidences the possibility of individual variations.