Final answer:
The upper motor neurons of direct tracts originate from the primary motor cortex of the frontal lobe, and they target the lower motor neurons.
Step-by-step explanation:
The upper motor neurons of all direct (pyramidal) tracts originate in the primary motor cortex of the frontal lobe. As outlined in the question's provided reference, these neurons are responsible for the conscious or voluntary movements of skeletal muscles and send motor commands through their axons to activate the lower motor neurons. The corticospinal tract is a key pathway for these neurons. Moreover, upper motor neurons target the lower motor neurons for further signaling to induce muscle movement, which ultimately causes skeletal muscles to contract in response to the commands.