Point 1 Intro Pathway Deficits Clinical Note Summary Overview Problems Contents  Anatomy

You need to keep in mind that lesions of the corticospinal tract do not destroy motor neurons that DIRECTLY innervate muscle. THERE IS NO DEATH OR ATROPHY OF MUSCLE. Corticospinal tract neurons are referred to as UPPER MOTOR NEURONS since they do not innervate muscle directly. In contrast, neurons in the ventral horn that DIRECTLY innervate muscle are called LOWER MOTOR NEURONS (LMN). When these neurons die there is ATROPHY OF THE MUSCLE.