Final answer:
The corticospinal and corticobulbar tracts originate from pyramidal cells, specifically Betz cells in the primary motor cortex. These neurons are pivotal for controlling voluntary skeletal muscle movements.
Step-by-step explanation:
The corticospinal and corticobulbar tracts project from the pyramidal cells, specifically from neurons located in the primary motor cortex known as Betz cells. These large cortical neurons are responsible for descending motor commands that control voluntary movement of skeletal muscles. The axons from these cells form the corticospinal tract, which projects to the spinal cord, and the corticobulbar tract, which projects to the brain stem. The corticospinal tract involves principally contralateral projections, while the corticobulbar tract involves ipsilateral projections.