Myelencephalon

The myelencephalon is a developmental categorization of a portion of the central nervous system. The myelencephalon is composed of the medulla; contains a portion of the fourth ventricle; as well as the glossopharyngeal nerve (CN IX), vagus nerve (CN X), accessory nerve (CN XI), hypoglossal nerve (CN XII), and a portion of the vestibulocochlear nerve (CN VIII).