Estimates have been made of the numbers and sizes of motor units in the thenar, hypothenar, and soleus muscles of patients with muscular dystrophy. The finding of a selective loss of motor units in these muscles could not have been due to nerve trauma since there was no evidence of sensory axon involvement in the median, ulnar, and posterior tibial (sural) nerves. The results of this study fully support earlier findings in the extensor digitorum brevis muscle and reinforce the concept of a neurogenic basis for muscular dystrophy.
Alan J. McComas, Roberto E. P. Sica, Adrian R. M. Upton. Multiple Muscle Analysis of Motor Units in Muscular Dystrophy. Arch Neurol. 1974;30(3):249–251. doi:10.1001/archneur.1974.00490330057009