From rostral to caudal the internal structures of the medulla will be briefly described from three levels: (1) level of the inferior olivary nucleus, (2) decussation of the internal arcuate fibers, and (3) decussation of the pyramids. Nuclei visible in a transverse section at the level of the inferior olivary nucleus include those associated with cranial nerves VIII (vestibulocochlear), IX (glossopharyngeal), X (vagus), XI (spinal accessory), and XII (hypoglossal) (eFig. 9.40). At this level, the medial lemniscus maintains a vertical position immediately adjacent to the midline. Dorsal to the medial lemniscus are the medial longitudinal fasciculus and hypoglossal nucleus. A large distinguishing structure at this rostral level is the laterally oriented inferior cerebellar peduncle, which connects to the cerebellum posteriorly.