Somatotopically located motor fibers in corona radiata: evidence from subcortical small infarcts.

Using T2-weighted MRI, we measured the relative anteroposterior distance of small corona radiata infarcts in 54 patients who had disproportionate weakness in the bulbar (Group A), arm (Group B), and leg (Group C) muscles. The lesions were differently (p < 0.01) located: Group A, most were located anteriorly; Group B, most were in the middle; and Group C, most were located posteriorly. These results suggest that motor fibers are somatotopically arranged in the human corona radiata.