Spinal and cranial nerves differ in their development, internal structure and the paths each take to the brain. Spinal nerves travel from their endings through bundles that run to the spinal cord and then into the brain. Cranial nerves emerge directly from the brain to innervate the head and neck.
In addition to the different pathways they follow, cranial nerves vary substantially in their organization. Unlike spinal nerves, they do not form from dorsal and ventral roots. Cranial nerves can have more than one ganglion, though some entirely lack a ganglion. Unlike spinal nerves, which attach to the central nervous system at regular intervals, cranial nerves connect to the brain in an irregular pattern.