Final answer:
The primary motor cortex sends motor commands through the corticospinal pathway, which passes through the pons. Collateral branches of these fibers synapse in the pons and project to the cerebellar cortex, where they are compared to actual motor performance. The output from the cerebellar nuclei sends descending signals from the red nucleus to the spinal cord.
Step-by-step explanation:
The motor commands from the cerebral hemispheres travel along the corticospinal pathway, which passes through the pons. Collateral branches of these fibers synapse on neurons in the pons, which then project into the cerebellar cortex through the middle cerebellar peduncles. Ascending sensory feedback, entering through the inferior cerebellar peduncles, provides information about motor performance. The cerebellar cortex compares the command to the actual performance and can adjust the descending input to compensate for any mismatch. The output from deep cerebellar nuclei projects through the superior cerebellar peduncles to initiate descending signals from the red nucleus to the spinal cord.