Medulla oblongata ventral aspect External structure Pyramid:contain pyramidal tract (corticospinal tract) Decussation of pyramid:formed by crossing fibers of corticospinal tract Olive:produced by underlying inferior olivary nucleus Anterolateral sulcus:rootlets of hypoglossal nerve emerge from it Posterolateral sulcus:rootlets of glossopharyngeal,vagus and accessory nerves emerge from itMedulla oblongata ventral aspect  Pyramid: contain pyramidal tract (corticospinal tract) Decussation of pyramid: formed by crossing fibers of corticospinal tract  Olive: produced by underlying inferior olivary nucleus  Anterolateral sulcus: rootlets of hypoglossal nerve emerge from it  Posterolateral sulcus: rootlets of glossopharyngeal, vagus and accessory nerves emerge from it External structure