Twelve pairs of cranial nerves are associated with the brain. The first two attach to the forebrain, and the rest are associated with the brain stem (Figure 1). Other than the vagus nerves, which extend into the abdomen, cranial nerves serve only head and neck structures.
In most cases, the names of the cranial nerves reveal either the structures they serve, or innervate, or their functions. The nerves are also numbered, using Roman numerals, from the most rostral (anterior, superior) to the most caudal (posterior, inferior). Click on the names of the nerves to learn more.