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A 55-year-old male patient presents with a history of weakness and clumsiness. Symptoms began several months earlier with difficulty buttoning his clothes, getting the car keys in the ignition, and performing other fine movements. He noticed that the muscles in his arm and forearm twitched under the surface, and cramped easily. Over the past few months is arms have continued to weaken and lose muscle mass. On examination he has diffuse wasting and weakness on both upper extremities, fasciculations, slight spasticity on arms and legs, and hyperreflexia with extensor plantar responses. The sensory, coordination, and cranial nerve examinations are normal. The underlying pathological process affects neuronal bodies in which of the following structures?
A. Anterior horn of the spinal cord, medial brainstem, and prerolandic cortex
B. Posterior horn of the spinal cord, lateral brainstem, and postrolandic cortex
C. Intermediolateral column of the spinal cord, dorsal brainstem and intralaminar thalamus
D. Clarke’s column of the spinal cord, dorsal pons, and cerebellar cortex
What is A: Anterior horn of the spinal cord, medial brainstem, and prerolandic cortex?