Final answer:
Descending motor pathways, including the corticobulbar and corticospinal tracts, pass through the internal capsule and the brain stem. The dorsal longitudinal fasciculus is another descending pathway that travels through the brain stem's gray matter to the spinal cord.
Step-by-step explanation:
Descending motor pathways, such as the corticobulbar and corticospinal tracts, carry motor signals from the cortical areas to the muscles and glands. These signals must pass through the internal capsule, which is a crucial segment of the descending motor pathway located between the caudate nucleus and the putamen within the brain's basal nuclei. Furthermore, connections with the motor pathway from the basal nuclei involve both direct and indirect routes to the GPI/SNr, which can facilitate or inhibit the activity of the thalamus, respectively.
It's important to note that the brain stem acts as a major conduit for major ascending and descending pathways between the spinal cord and cerebrum. Specifically, the dorsal longitudinal fasciculus is a major output pathway of the hypothalamus that descends through the brain stem's gray matter and into the spinal cord. This highlights the significant role the brain stem plays in connecting the central nervous system components.