Final answer:
The primary motor cortex contains Betz cells which synapse with lower motor neurons in the brain stem or spinal cord. The corticobulbar tract and corticospinal tract are the two descending pathways traveled by the axons of these Betz cells. The corticobulbar tract is ipsilateral while the corticospinal tract is contralateral.
Step-by-step explanation:
The primary motor cortex contains Betz cells, which are large cortical neurons. These Betz cells synapse with lower motor neurons in the brain stem or spinal cord. The axons of Betz cells travel through two descending pathways: the corticobulbar tract and the corticospinal tract. The corticobulbar tract projects from the cortex to motor nuclei on the same side of the nervous system, while the axons of the corticospinal tract largely cross the midline and synapse on the opposite side of the body.