Final answer:
Upper motor neurons originate from the motor cortex and their target is to synapse with lower motor neurons; the basal nuclei do not originate these neurons but regulate movement.
Step-by-step explanation:
The target of an upper motor neuron is to synapse with the lower motor neuron which in turn projects to the skeletal muscle in the periphery. This system is part of the motor pathways originating from the motor cortex in the frontal lobe of the brain, specifically from a group of neurons known as Betz cells. The motor cortex is responsible for initiating voluntary movements by connecting to lower motor neurons in the brain stem or spinal cord through the corticobulbar and corticospinal tracts.
The basal nuclei, premotor cortex, brain stem, and motor cortex all play a role in motor function, but the correct final answer in two line explanation in 300 words: The basal nuclei are not the origin point for upper motor neurons; they are involved in the regulation of movement rather than the initiation of voluntary muscle control. Therefore, the area of the brain not responsible for originating upper motor neurons is a) Basal nuclei.