Motor Vs Sensory Pathways

Motor and sensory pathways are anatomically and functionally distinct systems within the central and peripheral nervous system. The primary motor (corticospinal) pathway originates in the precentral gyrus (Brodmann area 4), descends through the corona radiata, posterior limb of the internal capsule, cerebral peduncles, and ventral pons, with 85-90% of fibers crossing at the pyramidal decussation to form the lateral corticospinal tract in the contralateral spinal cord. These upper motor neuron fibers synapse on alpha motor neurons in the anterior horn (lower motor neurons), which project through ventral roots and peripheral nerves to skeletal muscle. The extrapyramidal system (basal ganglia circuits, reticulospinal, vestibulospinal, and rubrospinal tracts) modulates voluntary motor output, controlling tone, posture, and movement initiation. Sensory pathways follow two major ascending systems: the dorsal column-medial lemniscus (DCML) pathway transmits proprioception, vibration, and discriminative touch ipsilaterally via fasciculus gracilis (lower body) and fasciculus cuneatus (upper body), synapsing in the medullary nuclei, decussating as the internal arcuate fibers, then ascending through the medial lemniscus to the ventral posterolateral (VPL) nucleus of the thalamus. The anterolateral (spinothalamic) system carries pain and temperature signals:...