Corticospinal fibers arise from cells in the surface gray matter of the cortex, pass into the depths of the cortex, and emerge on the anterior surface of the __________ region of the brainstem. They pass inferiorly through the pons and again move toward the anterior surface while in the medulla's ____________ tract. The fibers then decussate to a _______ero___________ position inside the cord. Interruption of corticospinal fibers on one side of the brain at the level of the rostral medulla or above is likely to produce paralysis on the _________ side of the body.