Pyramidal decussation:

point at the junction of the medulla and spinal cord where the motor fibers from the medullary pyramids cross the midline. The fibers then continue into the spinal cord primarily as the corticospinal tract.

Learn more:

2-Minute Neuroscience: Medulla Oblongata

Know your brain: Medulla oblongata

Know your brain: Corticospinal tract