Before revision: In the somatic nervous system, the cranial nerves are part of the PNS with the exception of the optic nerve (cranial nerve II) , along with the retina .
After revision: In the somatic nervous system, the cranial nerves are part of the PNS with the exceptions of the olfactory nerve and epithelia and theoptic nerve (cranial nerve II) , which are considered parts of the central nervous system based on developmental origin along with the retina .