The cranial nerves are the nerves of the brain and the brainstem, they relay information between the brain and parts of the body, mostly the head and the neck. Humans have 12 paired cranial nerves numbered with roman numerals (I - XII), and they are named according to their structure or function and they are based on their rostral-caudal (front to back) position (as shown in the diagram below). The names of the nerves are as follow; Olfactory nerve (I), Optic nerve (II), Oculomotor nerve (III), Trochlear nerve (IV), Trigeminal nerve (V), Abducens nerve (VI), Facial nerve (VII), Vestibulocochlear nerve (VIII), Glossopharyngeal nerve (IX), Vagus nerve (X), Accessory nerve (XI), and Hypoglossal nerve (XII). These are listed in the table to the right along with the function that they perform. These nerves can have either an afferent function, so information coming into the brain, so for example inputs to the brain from our eyes or ears, or the nerves have an efferent function, so information coming from the brain such as controlling our facial muscles.