Which neurons have cell bodies in the motor cortex and innervate spinal cord anterior horn cells?

Which neurons have cell bodies in the motor cortex and innervate spinal cord anterior horn cells?

• A. Lower motor neurons.
• B. Upper motor neurons.
• C. Sensory neurons.
• D. Interneurons in the dorsal horn.

Answer: (B)

Upper motor neurons are the neurons whose cell bodies sit in the motor cortex and whose axons descend to the spinal cord to synapse on the lower motor neurons in the anterior horn. This corticospinal pathway is what conveys voluntary movement commands from the brain to the muscles by modulating the activity of the anterior horn cells, which are the lower motor neurons that directly innervate skeletal muscles. In other words, the brain sends signals via upper motor neurons, they end on the anterior horn cells, and those lower motor neurons then activate muscle fibers. Sensory neurons have cell bodies in dorsal root ganglia and carry information toward the CNS, while interneurons in the dorsal horn participate in processing sensory signals, not in transmitting motor commands from the cortex.

Upper motor neurons are the neurons whose cell bodies sit in the motor cortex and whose axons descend to the spinal cord to synapse on the lower motor neurons in the anterior horn. This corticospinal pathway is what conveys voluntary movement commands from the brain to the muscles by modulating the activity of the anterior horn cells, which are the lower motor neurons that directly innervate skeletal muscles. In other words, the brain sends signals via upper motor neurons, they end on the anterior horn cells, and those lower motor neurons then activate muscle fibers. Sensory neurons have cell bodies in dorsal root ganglia and carry information toward the CNS, while interneurons in the dorsal horn participate in processing sensory signals, not in transmitting motor commands from the cortex.